Ophiolite

Because I am fat and ugly and have enough regard for others to spare them the trauma.

Wholly false logic. We do not know which specific conditions were necessary for the emergence of life on this planet. We therefore cannot, at this stage, know if such conditions have been met, are likely to be met, or can ever be met again. You cannot extrapolate meaningfully from a sample size of one.

I'm quite frightened of the Giuoco Piano in chess and go practically catatonic in the presence of a partial differential equation.

Excellent news. Using this 'guess' we dicsover there is no difficulty whatsoever in having large dinosaurs and pterosaurs with our user friendly currently applied 981m/sec/sec. Can we now have a productive discussion on something more substantial?

Correct. Yes. Your question reveals a fundamental misunderstanding as to the nature and origin of black holes. Black holes are the remains of stars that went supernova and balsted much of their mass into space. Therefore black holes are, of necessity, smaller than many existing stars. It collapses when the nuclear reactions that were sustaining the pressure that kept the star in hydrodyamic equilibrium stop. It then falls in on itself.....rather rapidly. Sorry, that made no sense at all.

I liked Gold's tilt at windmills. There is a lot of carbon in the mantle. There is no particular reason some of it should not migrate upwards. The helium data is odd, but there are alternative explanations. There is, indeed, a deep hot biosphere, although how large and active it is is ill defined. On balance I should not be surprised if some hydrocarbons do originate in the depths, by methods not yet clearly identified. I would be amazed if the majority of hydrocarbons originated in this way. One of the practices in oil exploration is to analyse potential source rocks, generally shales, for suitable organic material. There we find all the biological markers mentioned earlier in this thread and many more besides. These can be chemically linked to the petroleum reservoirs into which the hydrocarbons have migrated. The industry spends considerable sums of money carrying out such analyses, or certainly did so in the 70s and 80s when I was involved with that side of things. This is not an industry that knowingly throws money away. Mootanman brings up two objections that need to be challenged. Firstly he asserts that the Russians adopted this concept of hydrocarbon generation and thereby made many new finds. This is not wholly true. A segment of the Russian industry pursued these concepts for a time. I can find no evidence that it currently seen as viable concept within Russia. I base this on a) a (limited) literarure search that turned up little or nothing b) conversations with several (half a dozen) graduates of Moscow's Oil and Gas University, none of whom had ever heard of the theory. Secondly, the contention contained above that oil was thereby discovered in 'impossible' places. The story of oil exploration has always been one of finding oil in impossible places. This has much more to do with the shallow imaginations of many oil men than with the deep sources of hydrocarbons.

Certainly. You made four statements. I challenged those four statements. You responded with statements that were not relevant to the truth or falsehood of your original statements. . I'm having a hard time working through the flawed grammar of that to determine what you mean, but I'm reasonably sure it is not relevant at this point. You seem to have clarified one of your positions: our inability to reach the moon or Mars in ten years is an economic one and therfore ultimately a political one. So your disbelief is based upon a presumption that the political situation will remain unchanged. A remark by a former Prime Minister, popular in the UK with media and politicians alike, is "A week is a long time in politics." If we can finish the discussion of your original statments first, I will then entertain further discussion of your new points.

This is incorrect. The clue is in the name: rubble pile. Rubble pile asteroids are the result of multiple collisions between planetesimals, both differentiated and undifferentiated. They have high porosities. Primordial objects are coherent and dense. Eros is almost certainly an example of such. The last time I checked the consensus was that the majority of asteroids would be rubble piles.

I blame John Calvin.

Nevada.

This is wrong. You are neglecting the reduction in fuel between the first phase of acceleration and the second. Since there is less mass to accelerate then with the same applied force the speed will be doubled in less than half the time.

Most asteroids are thought to be rubble piles. Detonating a large explosive on, in, or next to one will most likely blow it apart. If the explosion is relatively small, most of the material will then gradually reassemble itself. You need slow, gentle acceleration, best provided by a mass driver using the asteroids own materials both to eject and the volatiles to provide power generation.

Not so. Radioactivity solved one of the biggest problems science was facing at that time. The evidence from geology was, as Hutton so eloquently expressed, of an Earth with "no vestige of a beginning,–no prospect of an end." The indications from evolution were that enormous lengths of time were necessary to achieve the observed diversity and complexity of life. This flew in the face of calculations of the planet's age based upon rate of cooling. Radioactivity resolved these contradictions and supported the observations from biology and geology. That is quite different from what is being proposed in this thread.

Antarctica isn't, Europe isn't, Australia isn't. So half of the continents meet this condition. Although you were not asking the question Moontanman provisionally answered his answer stands here too. The continents are continually colliding, assembling, splitting up, disassociating, re-assembling as a consequence of plate tectonics. The shapes are thus pretty much random. Have a look at past global geographies and you will not find your slight triangular pattern.

You are assuming they were more sensitive. The reverse could still have been true and they would still have died out. How many herring are there on the planet? Many millions. Wipe out the vast majority of them and you still have a viable breeding number available to repopulate the oceans. You don't, however, have enough to feed the appetites of large marine reptiles. Ergo, out they go.

Return of Hate, I share the confusion over exactly what you are asking. The subsurface is definitely there, otherwise there would be nothing to support the surface. I'm having problems accessing the paper, so that is no help. I am guessing that you are looking for some means of a) assessing probable subsurface geology based upon projection of outcrops, or b) assessing probable subsurface geology based upon seismic data, or c)assessing probable subsurface geology based upon various geophysical and geological methods and projections. Could you confirm this? Ah! I see you did provide an explanation of what you meant. Sorry for not picking up on that earlier. You say ""you don't know what goes on in the subsurface. You need to somehow assess the unknown. You may know the range of the porosity, but not its distribution. You may know other sources of information that can help you in assessing these uncertainties about the subsurface. " I think that matches up with c) above. You also said "assessing uncertainty does not need more explanation. its simple:" With respect, despite being a graduate geologist who has maintained their interest in the subject for more than four decades, I was hard pressed to understand what you meant. It is worth considering that the decision on whether a communication is intelligible is generally best left to the reader, not the writer. (I can clarify this point if you wish. )

Intelligent life would have evolved more rapidly and destroyed the biosphere at an earlier stage.

As has been pointed out by csmyth gravity plays a central role in planetary formation. The exact mechanisms are not yet delineated, but the underlying theme is not in dispute. The character of the planets discovered thus far are distorted by the nature and sensitivity of the detection systems. As these are improved and diversified we shall have a better handle on the true range of planetary system character. Using the current biased sample to support your hypothesis is wrong and wrong headed.

If you are going to move the goalposts each time I point out the logical inconsistencies of your posts we shall have a very short dialogue.

Your ignorance on this point is surprising. You appear to have done some reading of the geological literature relating to plate tectonics, yet you are wholly unaware of the process of obduction, or the significance of ophiolite suites. Ancient ocean floors, 'scraped' onto continental masses during the subduction process are found in many locations around the planet, with many differing ages. These references may help to educate you in the matter. Perhaps them you will retract your amazement at the absence of ancient ocean floor. We don't just have evidence for ancient ocean floor - we have the ocean floor. The late Creataceous Oman ophiolite. Ordovician Appalachian ophiolites. The Bay of Islands ophiolite. The Ballantrae ophiolite. The Troodos ophiolite. And here is a general review of accretionary tectonics: Accretionary orogens in time and space. There are many more examples. You seemed to think you had a very telling point to make about the absence of ancient ocean floors. The ease with which it is dismissed causes me to doubt, in advance, the other points you have raised. Do they have a similarily flimsy basis?

Almost anything your heart desires. Volatiles: For life support - H2O, N2, O2 For propulsion - H2, O2, CH4, CH3OH For agriculture - CO2, NH4OH, NH3 For metallurgy - CO,H2S,Ni(CO)4,Fe(CO)5,H2SO4,SO3 For refrigeration SO2 Metals: For construction - Fe, Ni Precious metals - Au, Pt, Pd, Os, Ir, Rh, Ru, Re, Ge Semi-Conductors Si, Al, P, Ga, Ge, Cd, Cu, As, Se, In, Sb, Te Based on Table 1, Ross, S.D. Near-Earth Asteroid Mining Ross references this paper: J. S. Kargel, Semiconductor and precious-metal resources of metallic asteroids, Princeton Conf. on Space Manufacturing, Space Studies Inst., 1997. In it Kargel estimates the value of a 1km metallic asteroid as "exceeding that of the worlds proven economic reserves of nonmetallic and metallic mineral resources". Or you may like a more modest proposalsuch as robotic mining of a couple of thousand tons of volatiles which are moved to low Earth orbit to provide raw materials for early stage space industrialisation. Sorry Swanson, I was composing my response when you posted your note. Delete my post if you wish, but frankly I find lemur's question to be on topic. I interpret the OPs interest as twofold, in both the mechanics and the economics of the process.

I'll have to dig around. To my thinking it is old, established thought, almost self evident. Digging done. It seems I was over (under?) enthusiastic. Jupiter has eight regular satellites, not the four I suggested. Regular satellites are ones with prograde orbits and minimal eccentricity. The four Galilean satellites are, as I noted, definitely regular, plus a further four. (See, for example,Origin and history of the Outer Planets, page 396.) Attempts to explain the irregular satellites are still ongoing. For example, Nesvorny,D. et al Capture of Irregular Satellites During Planetary Encounters, The Astronomical Journal, May 2007. They note their proposed mechanism would not explain the origin of the Jovian irregulars, but implicitly accept these are captured asteroids (or small comets).

That would rather depend upon what happened to Gondwanaland. Would India have retained its same latitude? Certainly there would be know Indo-Gangetic plain and probably no Deccan platea, which together pretty much define Indian geography.

You are one of those people who think Archimedes actually cried out "Eureka" as he ran down the street having just discovered the displacement principle now named after him.

Since I've read everything he wrote I can't really read more.