Posted by Walker on July 13, 1998 at 01:57:31:
In Reply to: answers posted by Robert O'Brien on July 10, 1998 at 00:01:47:
:2) What proponents of abiogenesis lack is an "intermediate form/organism." This supposed
organism must be in between inorganic molecules--which generally have no tendency to
replicate themselves (even when they do "replicate," such as in a crystal, there is no variation
in that process, hence no natural selection)--and complex organisms like ourselves. Even the
"simplest" organisms of today are incredibily complex, and cannot be accounted for at the
"beginning." This professor said that he and his colleagues have _faith_ that such an organism
can be found, but, as of yet, have no evidence to that end.
:3) The probability of such an event occuring is astronomical. Being a mathematician, I can
safely say that with the estimates I have seen thus far, you couldn't even imagine the number of
lives you'd have to live to count to such an enormous number. More than a few scientists (who
obviously reject abiogenesis) have speculated that there is not enough matter in the universe for
abiogenesis to occur (anywhere). The usual retort to this is: "Well, we are here, so that's the
proof!" Well, I find such an argument hokey at best. We are here, but that does nothing in the
way of supporting abiogenesis. If you really believe we are that 1 in 1x10^58 chance, then go
ahead.
:The data behind that number can be found at
http://www.geocities.com/CapeCanaveral/Lab/6562/problife.html. It was compiled by Dr.
Hugh Ross, an astrophysicist. I have seen a similar estimate from another source.
Thank you. I checked out this page which is really a discussion of the probability that advanced life could form somewhere in the universe. This is an interesting question but much broader than the one I hoped to discuss (abiogenesis given our present earth/solar system setup) I was hoping you had a probability calculated for the intermediate organism described in your point 2 above.
But since you brought up the big picture, let’s discuss it.
:You really show how ignorant you are here. Who in the hell are you to tell me, an applied
mathematics major, that 1x10^58 is a small number? Guess what, pookie, the mass of the
known universe is approximately 1x10^53 kilograms. 1x10^53 is only 1/100000 of the number
I cited.
The mathematics involved may intimidate some: multiplication of no less than 40 constants. Decimal point arithmetic skills will be needed Knowledge of exponential notation and probability will be useful. Those who haven’t passed the seventh grade proceed with caution!
The criticisms I would give for Ross’ probability estimate, 1x10^-58 (the Ross number) are as follows:
1) Ross assumes that the formation of life requires a planet nearly identical to ours and must exist in a solar system nearly identical to ours. Ross doesn’t account for the possibility of differing evolutionary paths that could adapt to colder, hotter planets, planets with greater escape velocity, greater radio bombardment, etc.
2) Ross doesn’t provide reasonable ranges for his estimates to fall into, that is an optimistic guess and pessimistic guess. Rather boldly asserts hard constants in a field of study which is barely more than speculation.
3) Ross’ most egregious error is treating dependent events as if they were independent. For example, Ross includes the probability the mass of the parent star, the age of the parent star and the color of the parent star. But the color of the star is dependent on mass and age! That is if the star has about the same age and mass as our sun, the probability that it will be yellow is 1. But Ross includes color as independent variable and gives it a probability of 0.4.
This would be similar to saying if the probability that a person sees God is 1.0x10^6 and the probability of seeing the face of God is 1.0x10^6 then the probability of seeing both God and the face of God is 1.0x10^12 But this is wrong since the two sightings are dependent on each other. If one sees God, one most likely sees his face also. (But not always, as when God mooned Moses, Exodus 33:17-23) You can see how this misuse of probability can lead to extreme inaccuracy.
4) Ross omits one very important factor. He has made his calculation as if there were only one chance for it to happen; one chance right here and now. The fact is, there are billions and billions of stars, hence billions of opportunities for life to get a chance. The odds of rolling a 6 on a six sided dice is 0.17 but if you get a billion tries, the chance that you roll a six is virtually 1 (or 100%) Ross has failed to multiply his number by an estimate of the number of planets in the universe.
I will now correct some errors to Ross’ rationale and provide my more optimistic factors
1. Galaxy Type
if too elliptical: star formation would cease before sufficient heavy element build-up for life chemistry, if too irregular: radiation exposure on occasion would be too severe and heavy elements for life chemistry would not be available
Ross’ guess (p = 0.05)
A survey of the nearest galaxy cluster (Virgo) shows that out of the 60 most massive galaxies, 20 are of type Sb (Milky way type galaxies)
Walker’s estimate (0.3)
2. Supernova proximities and frequencies
Ross’ estimate: (p = 0.01)
3. Supernova dates
Ross’ estimate:(p = 0.2)
4. White dwarf binaries proximities
Ross’ estimate: (p = 0.05)
5. White dwarf binaries dates,
Ross’ estimate: (p = 0.2)
Items 2-5 are all dependent on galaxy type. Given an Sb type galaxy, these probabilites are near 1.
Walker’s estimate(p=1)
6. Parent star distance from center of galaxy
if farther: quantity of heavy elements would be insufficient to make rocky planets
if closer: galactic radiation would be too great; stellar density would disturb
planetary orbits out of life support zones
Ross’ estimate: (p=0.2)
Spiral arms of Sb galaxies are composed of blue (heavy element forming) stars. Since the arms reach from center to edge of galaxy, heavy elements are abundant throughout. Also, many stars have highly elliptical orbits.
Walker’s estimate (p=0.9)
7. Number of stars in planetary system
if more than one: tidal interactions would disrupt planetary orbits
if less than one: heat would be insufficient for life
Ross’ estimate (p=0.2)
A survey of the sky shows the ratio of single stars to multiple star systems at 0.5. Note however that mathematics predicts planets can maintain stable orbits around multiple systems if their distance is greater than 5 AU. It is debatable if planets could form in a close binary system however. Estimates for the # of planets in the universe do not include planets with no Sun therefore no need to worry about that scenario.
Walker’s Estimate (p=0.5)
8. Parent star birth date
if more recent: star would not yet have reached stable burning phase; stellar system would contain too many heavy elements. if less recent: stellar system would not contain enough heavy elements
Ross’ estimate: (p=0.2)
Accept Ross’ less recent argument, but not more recent since it’s not at all clear that there can be too many heavy elements.
Walker’s estimate (p=0.5)
9. Parent star age
if older: luminosity of star would change too quickly
if younger: luminosity of star would change too quickly
Ross’ estimate: (p= 0.4)
Walker’s estimate (p=0.4)
10. Parent star mass
if greater: luminosity of star would change too quickly; star would burn up too rapidly
if less: range of distances appropriate for life would be too narrow; tidal forces would
disrupt the rotational period for a planet of the right distance; uv radiation would be
inadequate for plants to make sugars and oxygen.
Ross’ estimate (p=0.001)
Our sun is slight larger and brighter than the typical star. Type O, B and A stars burn out too quickly but these are rare in the universe. Life could most likely survive on cooler type F stars, G (our sun), K and on hot M stars. These types make up the majority of stars in our galaxy.
Walker’s estimate: (p=0.5)
11. Parent star color
if redder: photosynthetic response would be insufficient
if bluer: photosynthetic response would be insufficient
Ross’ estimate: (p = 0.4)
Star color is a function of mass and age, this has already been included.
Walker’s estimate (p=1) given correct mass and age.
12. Parent star luminosity relative to speciation
if increases too soon: would develop runaway greenhouse effect
if increases too late: would develop runaway glaciation
Ross’ estimate: (p=0.0001)
This is a function of Star mass, age which we have already included and distance from planet to star and atmosphere makeup which we will include later. Note that earth has gone through cooling and warming ages without entering a "runaway" stage and in spite of a gradual and continual heating up of the sun.
Walker’s estimate (p=1)
13. Surface gravity (escape velocity)
if stronger: planet's atmosphere would retain too much ammonia and methane
if weaker: planet's atmosphere would lose too much water
Ross’ estimate: (p = 0.001)
Methane, ammonia and water vapor are broken up by UV radiation in spite of a planet’s surface gravity. hydrogen escapes into space. The carbon dioxide dissolves in the oceans or is absorbed by the crust leaving a Nitrogen atmosphere. Yet we should probably have some upper limit on surface gravity. Lower limit is needed as water vapor and other compounds could not be maintained..
Walker’s estimate: (p = 0.3)
14. Distance from parent star
if farther: planet would be too cool for stable water cycle
if closer: planet would be too warm for stable water cycle
Ross’ estimate: (p = 0.001)
Planet could be further away with a hotter sun or closer with a cooler sun.
Walker’s estimate: (p=0.5)
15. Inclination of orbit
if too great: temperature differences on the planet would be too extreme
Ross’ estimate: (p = 0.8)
Walker’s estimate (p=0.8)
16. Orbital eccentricity
if too great: seasonal temperature differences would be too extreme
Ross’ estimate: (p = 0.3)
Orbital eccentricities for all 9 planets show little temperature variation even though most follow paths more eccentric than earth. Earth’s eccentricity varies in a period of 93,000 years but stays fairly circular as do most of the planets. Triton has been observed to vary by a few degrees.
Walker’s estimate: (p=1)
17. Axial tilt
if greater: surface temperature differences would be too great
if less: surface temperature differences would be too great
Ross’ Estimate: (p = 0.01)
Earth’s axial tilt varies with between 22 and 28 degrees with a period of 41,000 years. Life isn’t stressed. Of the 9 planets, half have axial tilts in this range. Seems to be the rule in solar system formation.
Walker’s estimate: (p=0.5)
18. Rotational period
if longer: diurnal temperature differences would be too great
if shorter: atmospheric wind velocities would be too great
Ross’ estimate: (p = 0.1)
Rotational period dependent on distance from the sun (Mercury, Venus spin slowly, Jupiter rapidly, Earth and Mars intermediate) Distance from Sun is already included.
Walker’s estimate (p=1)
19. Rate of change in rotational period
if larger: surface temperature range necessary for life would not be sustained
if smaller: surface temperature range necessary for life would not be sustained
Ross’ estimate: (p = 0.05)
Rate of change in rotational period is very near zero as are most bodies in motion.
Walker’s estimate (p=0.9)
20. Age
if too young: planet would rotate too rapidly
if too old: planet would rotate too slowly
Ross’ estimate: (p = 0.1)
Rotational considerations have already been included! BTW, rotation is not a function of age as evidenced by the planets in our solar system which are all of the same age. Mars rotates about the same as Earth, Mercury much slower, Venus even slower (actually rotates backwards from the rest of the planets) More distant planets rotate more rapidly Rotation has already been included.
Walker’s estimate: (p=1)
21. Magnetic field)
if stronger: electromagnetic storms would be too severe
if weaker: ozone shield and life on land would be inadequately protected from stellar
and solar radiation
Ross’ estimate: (p = 0.01)
Or life would evolve with protection against radiation. Or generate a different atmosphere shield.
Walker’s estimate: (p=0.1)
22. Thickness of crust
if thicker: too much oxygen would be transferred from the atmosphere to the crust
if thinner: volcanic and tectonic activity would be too great
Ross’ estimate: (p = 0.01)
All rocky planets go through a gaseous, liquid, crust-forming evolution. The thickness of crust is a function of age, mass, and distance from Star. (Already included)
Walker’s estimate: (p=1)
23. Albedo (ratio of reflected light to total amount falling on surface)
if greater: runaway glaciation would develop
if less: runaway greenhouse effect would develop
Ross’ Estimate: (p = 0.1)
Greenhouse problem is a function of atmosphere composition not albedo. Venus is a green house because its atmosphere contains carbon dioxide. It’s albedo is actually double earth’s (reflects twice as much light)
Walker’s estimate (p=1) (not really a factor)
24. Collision rate with asteroids and comets
if greater: too many species would become extinct
if less: crust would be too depleted of materials essential for life
Ross’ estimate: (p = 0.1)
crust formed with same materials found in comets and asteroids. More impacts = more frequent rebounding of life; probably resulting in impact resistant species. (warm blooded creatures?)
Walker’s estimate (p=1) (non factor)
25. Rate of change in collision rate with asteroids and comets
if greater: not enough materials essential for life would have been brought to Earth
if less: collisions would cause too many species to become extinct
Ross’ estimate: (p = 0.1)
Walker’s estimate: (p=1) Same as 24. (non factor)
26. Oxygen to nitrogen level in atmosphere
if larger: advanced life functions would proceed too quickly
if smaller: advanced life functions would proceed too slowly
Ross’ estimate: (p = 0.1)
Oxygen to nitrogen levels was generated by life. Oxygen has been increasing at the rate of 1% every 36 million years. Life continues to thrive.
Walker’s estimate (p=1) Life creates its own oxygen/nitrogen atmosphere
27. Carbon dioxide level in atmosphere
if greater: runaway greenhouse effect would develop
if less: plants would be unable to maintain efficient photosynthesis
Ross’ estimate: (p = 0.01)
Carbon dioxide was absorbed by crust and oceans
Walker estimate: (p=1) Given earth’s mass and proximity to sun (already included).
28. Water vapor level in atmosphere
if greater: runaway greenhouse effect would develop
if less: rainfall would be too meager for advanced life on the land
Ross’ estimate: (p = 0.01)
Walker’s estimate: (p=1) Similar to 27.
29. Atmospheric electric discharge rate
if greater: too much fire destruction would occur
if less: too little nitrogen would be fixed in the atmosphere
Ross’ estimate:(p = 0.1)
Walker’s estimate:(p=1) Dependent on previously included parameters.
30. Ozone level in atmosphere
if greater: surface temperature would be too low
if less: surface temperature would be too high: there would be too much uv radiation at the planet's surface
Ross’ estimate: (p = 0.01)
Walker’s estimate: (p=1) Dependent on previously included parameters.
31. Oxygen quantity in atmosphere
if greater: plants and hydrocarbons would burn up too easily
if less: advanced animals would have too little to breathe
Ross’ estimate: (p = 0.01)
Walker’s estimate:(p=1) Same as 26.
32. Tectonic plate activity
if greater: too many life forms would be destroyed
if less: nutrients on ocean floors (from river runoff) would not be recycled to the continents through tectonic uplift
Ross’ estimate: (p = 0.1)
Walker’s estimate: (p=1)Dependent on planet age, composition, rotation (already included)
33. Oceans to continents ratio
if greater: diversity and complexity of life forms would be limited
if smaller: diversity and complexity of life forms would be limited
Ross’ estimate: (p = 0.2)
Walker’s estimate: (p=1) limited but not inhibited.
34. Global distributions of continents (for Earth)
if too much in southern hemisphere: seasonal temperature differences would be too
severe for advanced life
Ross’ estimate: (p = 0.2)
Forces of Equilibrium cause land masses to separate, earth spin forces them to equatorial positions.
Walker’s estimate:(p=0.9)
35. Soil mineralization
if too nutrient poor: diversity and complexity of life forms would be limited
if too rich: diversity and complexity of life forms would be limited
Ross’ estimate: (p = 0.1)
Life thrives and diversifies everywhere on earth despite varied degrees of mineralization on the planet Walker’s estimate: (p=1).
36. Gravitational interaction with a moon
if greater: tidal effects on the oceans, atmosphere and rotational period would be too
severe
if less: orbital obliquity changes would cause climatic instabilities; movement of
nutrients and life from oceans to the continents and continents to the oceans would
be insufficient; magnetic field would be too weak
Ross’ estimate: (p = 0.1)
Rotational and nutritional parameters already included. Organisms adapt to radiation
Walker’s estimate:(p=1) (non-factor)
37. Jupiter distance
if greater: too many asteroid and comet collisions would occur on Earth
if less: Earth's orbit would become unstable
Ross’ estimate:(p = 0.1)
Asteroid/comet collisions already included. Mars’s orbit stable for 5 billion years despite being much closer to Jupiter.
Walker’s estimate (p=1) (non-factor)
38. Jupiter mass
if greater: Earth's orbit would become unstable
if less: too many asteroid and comet collisions would occur with Earth
Ross’ estimate: (p = 0.1)
Same as 37. Note that the Sun gobbles up many times as many comets as does Jupiter.
Walker’s estimate: (p = 1) (non-factor)
39. Eccentricity of Jupiter and Saturn's orbits
if greater: Earth's orbit would become unstable
Ross’ estimate: (p = 0.05)
Walker’s estimate: (p=1) ( Same as 37)
40. Longevity requirements
Ross’ estimate: (p = 0.0001)
Life thrives in spite of asteroid bombardment, solar radiation, heat, cold, plate techtonics, etc. Those things don’t seem like much because life has adapted to every one of them. There is no reason to believe life couldn’t adapt to changing conditions such as ice ages, etc.
Walker’s estimate: (p=1) (non-factor)
Ross’ Total Probability = 1:10^58
Walker’s Total Probability (life conditions met for a given star in the Universe) = .00007
Multiply by 1x10^11 (# stars/per galaxy) = 7 million stars expected to sustain life per galaxy.
At this point, someone may ask, "Who the hell are you, Walker, to question Dr. Ross, an Astrophysicist?"
My response is that in addition to passing the seventh grade and reading an astronomy book, I was elected chief of playground equipment in 3rd grade.
But for those of you who like the word of an authority here is another estimate from Michael A. Seeds, Joseph R. Grundy observatory. He writes Astronomy text books for a living; This one from "Horizons: Exploring the Universe" Third Edition.
The Number of Technological Civilizations per Galaxy
C = N*P*L*B*I*S
Estimates
Optimistic Pessimistic
N Stars/Galaxy 2x10^11 2x10^11
P %Stars w/planets 0.01 0.5
L %planets/star w/ sufficient longevity 0.01 1
B %planets/star capable of life 0.01 1
I %life w/intelligence 0.01 1
S %starlife while intelligence survives 1x10^-8 1x10^-4
C communicative civilization/galaxy 2x10^-5 1x10^7
Of course this whole discussion is highly speculative and not germane to the issue at hand: ABIOGENESIS
Whether it just happened, or God put it there, the earth is there; with it’s axial tilt, orbit, moon, atmosphere, etc. What is uncertain is how could life form by itself given what we know about the earth and its environment. What the opponents of primordial soup need to provide is something like this
Is the Chemical Origin of Life a Realistic Scenario?
…Or maybe a probabilities breakdown like Ross’ … What are the odds of having a reducing atmosphere? What are the odds that amino acids would form? What are the odds that proteins would form from amino acids? What is the probability of cell walls forming? What is the probability of RNA becoming enclosed inside a cell wall? Etc.