Ophiolite

I agree. I like bandwagons, but I can't jump as high as I used to.

I'm trying to find you solid data on the first question. Around 70-80% of meteorites are stony. I would expect much the same mix amongst asteroids, which they are derived from. To complicate the matter some asteroids are derived from the break up of comets that have lost all or most of their volatiles. There is increasing recognition that the comet/asteroid dichotomy is not necessarily a simple division, but I can't get a good handle yet on what current thinking is. (Give me a few days.)

Wrong place

Pioneer, milestones are arbitrary points on a continuum, placed there by humans for their convenience in understanding the spectrum and because of our innate tendency to classify. Now could you address the two points I asked you to address. Just to remind you: Point 1: Progress implies direction and better. Such terms are frowned upon in an evolutionary context. Point 2: surely all that is required for your two cell critter to go to a ten cell critter is to tweak the hox genes. How then do you distinguish that from a similar tweak for your bird colouration?

I shall set aside completely the possibility that alien life forms may enjoy a wider range of temperature tolerances as the consequence of a different (perhaps radically different) biochemistry. There are several ameliorating influences on temperature. Widdekind makes the central point about water. Martin mentions albedo changes and is probably thinking in terms of cloud/ice cover variations, but I would add possible changes in vegetative reflectivity with the eccentric seasons. Martin also mentions greenhouse effects. I'll add, what if the alien 'vegetation' had evolved to emit significant quantities of methane in response to falling temperatures. These sort of variations permit a vastly wider range of 'natural' temperatures for the HZ that will still translate into variations that fall within the range that concerns you. Finally, we are talking about the habitable zone. That is not the multi-cellular HZ, but the HZ. Thermophiles would have no problems in the 40 to 80 degree range. No one has addressed the issue of a migrating HZ. The HZ must migrate because the luminosity of the star varies over time. If we are interested in finding planets capable of sustaining the kind of multicellular life that interests Mokele, with suitably scaly skin and cold blood, then it is not where the HZ is today, but where was it 1 billion years ago and where will it be one billion years in the future. This will seriously reduce the size of the viable zone. (If I wanted to dismiss my own argument I would just mutter Gaia and be done with it.)

I'm going to take a wild assed guess here, Truedeity. Your opening post was interesting and its tenor excellent. You offered a speculation, but you did so in a self-deprecating manner. That was very encouraging. Why was that important? This and other forums have been filled with nonsense by people who 'have a theory'. (iNow and Phi for All both offered friendly advice on the dangers of calling your own speculation a 'theory'.) Then, enter stage left, the banned and discredited Tom Vose. In apparent response to his post you offer up a lengthy piece that includes the words "I have been made angry. To anyone that cares. I have no more time for toddler minds." Whether you intended it or not, that pretty well identified you as a classic "I have a theory" woo-woo. Then you resurface 3 months later as if nothing had happened. Status? No one gives a damn. You might try apologising to iNow and Phi for All for implying that they were toddler minds. You might try reining in your ego. You might try keeping a clamp on your temper. I don't think it will do much good, but I suspect it's the only course of action that might.

No idea. Maybe it's turtles all the way down.(On this thread I'm a reporter, not a commentator.)

No one has yet commented on Nick Bostrom's intriguing 2003 paper, "Are You Living In a Computer Simulation", published in Philosophical Quarterly. Here is the abstract: A technologically mature “posthuman” civilization would have enormous computing power. Based on this empirical fact, the simulation argument shows that at least one of the following propositions is true: (1) The fraction of human-level civilizations that reach a posthuman stage is very close to zero; (2) The fraction of posthuman civilizations that are interested in running ancestor-simulations is very close to zero; (3) The fraction of all people with our kind of experiences that are living in a simulation is very close to one. If (1) is true, then we will almost certainly go extinct before reaching posthumanity. If (2) is true, then there must be a strong convergence among the courses of advanced civilizations so that virtually none contains any relatively wealthy individuals who desire to run ancestor-simulations and are free to do so. If (3) is true, then we almost certainly live in a simulation. In the dark forest of our current ignorance, it seems sensible to apportion one’s credence roughly evenly between (1), (2), and (3). Unless we are now living in a simulation, our descendants will almost certainly never run an ancestor-simulation Source: http://www.simulation-argument.com/simulation.html This concept admits of intelligent design without invoking a god. (I am routinely perplexed by the tendency of atheists and agnostics to assume that any intelligent designer is equivalent to a God, generally of the conventional, Abrahamic disposition. Very channeled thinking. Not good.)

I believe you are correct.

If only I had known. Nevertheless, Pioneer if you will make an honest attempt to address my two points you may have an advocate at the hearings that cannot be too far away.

I was raised as a Protestant in the Church of Scotland and am now a lapsed agnostic. I see no conflict between science and the Bible. I never have. I was taught that the Genesis story, like so much in the Bible, was a metaphor. I understood that the Bible, while it might be God's word, had been filtered through human understanding that could add confusion and ambiguity. By all means follow your Christian leanings. The ethical principles of the mainline churches are for the most part sound. (I exclude the unacceptable position of the Catholic Church on birth control.) If you can gain comfort and confidence from your beliefs and be a better member of society as a result, then great. But also heed iNow's advice. Seek a better understanding of the physical reality of the world as revealed by science. It has been very succesful in the past and will be more succesful in the future. There is no reason you cannot pursue both avenues, the spiritual and the scientific. Just avoid getting them confused. Oh, and you are definitely not crazy. No one who tries to think for themselves is crazy.

Refer to my earlier post. Kinetic energy, energy of motion, is converted to thermal energy and shock waves. Remember the equation is Energy = 0.5 x mass x Velocity ^2.The objects are travelling very fast - typically 20km/sec. Square that an d you get a very big number. At that speed, hitting the atmosphere for a small object is like hitting a brick wall. The object explodes violently. You say you can't imagine this. Don't. I'll assume you have Excel or some similar spreadsheet program. Create a small routine where you enter the diameter of the asteroid and its density. (Volume of a sphere = 4/ pi r^2). I used these values for density. Iron7.5 Stony-Iron4.5 Chondrite3.5 Carbonaceous Chondrite2.95 You can then calculate the mass of the asteroid. Offere a range of velocities, use the equation I gave above and there you have your energies. You no longer have to imagine, you can see what happens when one or other variable changes.

Nick, Some random thoughts for you. 1. Welcome. 2. Your speed of light figure is way out. You are quoting the supernova ejection speed as 1805978 miles per second and say this is 1/166 the speed of light. That would make c = 300,000,000 miles per second, approximately. Curiously enough this is the speed of light in metres per second, not miles per second. 3. There is no good reason to assume the ejection of any material due to an event at the central black hole would be at the same speed as from a supernova. It might be faster, it might be slower. Since the mechanisms are quite different there is no reason the speeds should be similar. Unfortunately that rather invalidates your whole idea. 4. We know to the distance to the galactic centre quite accurately. Before the Keck telescopes allowed us to make infrared observations the galactic centre was obscured by dust and the closest we could come was to say around 8 kiloparsecs. The figure hasn't changed, but we are now much more confident of its precision. (8.0 +/- 0.6 kpc) 5. Your underlying thinking is sound: events detected by em radiation may pressage consequences that travel more slowly. 6. Any 'intense radiation' is going to arrive at the same time as the light and other em radiation signalling the event. 7. One of the great concepts in written English is the paragraph. If you had used some you might have had more replies. 8. Overall - and I mean this kindly - your thesis highlights the dangers of indiscriminate pot smoking.

Pioneer, could you address the points I raised in my earlier post. First (and this is echoed by Mokele's first post in the thread) how do you justify the implication of progress in your thesis? Second, expressed more generally, why do you seem to believe that large phenotype changes always require large genotype changes?

Pure limestone is pure calcium carbonate. A limestone quarry is likely to have limestone with a very high level of purity. Go for one that is crystaline with a low fossil content. What level of purity do you need?

Go to a limestone quarry.

I am having real problems getting past this. Progress implies direction and better. Such terms are frowned upon in an evolutionary context. Please correct me if I am wrong - this is not my strongest field - but surely all that is required for your two cell critter to go to a ten cell critter is to tweak the hox genes. How then do you distinguish that from a similar tweak for your bird colouration? I shall be interested to see what others think, but for me you have introduced an unnecessary complication that adds nothing to our understanding of the process of evolution.

Absolutely this is a factor and I know there has been research done on it. I'm trying to locate something solid right now. In a related area, I know that the angle of impact has little effect upon the shape of the resultant crater if the bolide makes it all the way to surface. You wind up with a roughly circular crater whether the object comes in at 90 deg or 20 deg. I think at very low angles (<15 or 20) there is an assymetry to the resultant crater, but it is not a big effect.

DH has rightly pointed out that there has been much nonsense talked in this thread (as well as some very pertinent points). Here, in no particular order, are some hard facts regarding bolide impact. (I’m using the general term bolide, since it covers comets, asteroids and anything in between.) The energy of the impact is determined by the kinetic energy of the body, which is in turn proportional to 0.5mV ^2. So a small difference in velocity can produce a large difference in the magnitude of the impact. For example: a 5m diameter carbonaceous chondrite impacting at 12 km/sec (close to the slowest possible impact speed) will produce around 1.4 E13 joules. At 24km/sec this rises to 5.6 E13 joules, four times the impact energy. If the impactor was an iron this would rise to 1.4 E14 joules. These values are about the same as that of the Hiroshima atomic bomb – from a 5m diameter object. A 1.5 km diameter asteroid, impacting at 20 km/sec would deliver as much energy as the Earth releases each year through volcanism, heat flow and earthquakes. (1.3 E21 joules) The exceptional Christmas Eve earthquake in Indonesia released 2.0 E18 joules, about what you would get from a 200m diameter chondrite asteroid impacting at 17km/sec. Such impacts (200m) will occur every ten thousand years or so. At the upper size range (50m diameter)for this most recent visitor, an impact would have generated around 5.0 E16 joules, equivalent to ten ‘typical’ hydrogen bombs. A couple of points on impact velocity. This cannot be lower than the escape velocity of the Earth, which is about 11 km/sec. The maximum impact velocity is a combination of the Earth’s velocity around the sun (30km/sec) and the solar system escape velocity at the Earth’s orbit (42 km/sec), giving a maximum of 72 km/sec. Since most asteroids tend to be travelling in much the same direction as the Earth actual impact velocities for these are lower, typically in the range of 15 – 25 km/sec. Anything less than 50m in diameter is unlikely to make it through the atmosphere without exploding. Larger bodies may also break up if they are loose rubble masses, as many asteroids and comets are now thought to be. The frequency of impacts is as topic provoking much debate. Data are sparse and we have only acknowledged the possibility of such events in the last few decades. An impact from an object such as the one we are discussing might be expected every couple of hundred years, so even if this one had hit any damage would be localized. (Which is not in any way intended to understate the devastation that would occur locally, just to point out that the global effect would be minimal to non-existent.) A Tunguska sized strike is estimated to occur from every 200-300 years (Bryant, E. 2008 Tsunami, The Underrated Hazard. Praxis Publishing p234) to every 1900 years (French, B.M. 1998 Traces of Catastrophe. The Lunar and Planetary Institute Table 2.1) There is a lot more that could be said, but that should do for starters. I have to eat.

I presume this is Dead On Arrival. If the battery is totally lifeless when you receive it you have a certain time period in which to claim a replacement. No point in calling them three months later to say it didn't work. They might still replace it, but you would be out return postage, packing charges, etc. Please note this is a wild ass, shoot from the hip, guess.

The KT impactor was around 10km in diameter. All suggestions to 'nudge' asteroids out of the way have failed to take into account the fact that most asteroids are rubble piles that would fly apart if you sneezed at them. Which would you prefer? A single large impact that takes out Berlin, or several small impacts that take out much of Europe? The factor of 10x is for the magnitude of the greatest amplitude of horizontal displacement. That, as Sisyphus has pointed out, is different from the energy of the event.

6.7km is not that deep. Around 22,000'. Pore pressure at this depth would be around 10,000 - 11,000psi; maximum matrix stress (the 'load' in the solid part of the rock) would be around 11,000 - 12,000psi. Since the fossils are fully embedded in the fabric of the rock - they are the fabric of the rock - then they can tolerate a lot. Pressure at this depth is mainly going to distort the shape of the fossil; the temperature, in conjunction with the pressure, is going to cause mineral changes, but that's what fossilisation is. The main issue is that, if these rocks are 2.7 my old, then almost certainly these rocks were originally deeper and were subjected to higher pressures and temperatures. At 22,000' we are still probably in the realm of diagenesis. Much beyond that we are likely experiencing full blown metamorphism. That would be expected to destroy fossils, or greatly reduce their preservation quality. Strictly speaking the more important issues are - a)metamorphism' date=' corrupting the samples. b) microscopic character of precambrian fossils c) greater difficulty of preserving microfossils. There are plenty of old rocks at the surface in the shield areas around the world. They just suffer from points a) through c). I think some older ones have been found. I can't immediately put my hand on the reference. (I'm not thinking of the isotope clues from the Issua formation in Greenland.) Absolutely.

YT you seem to have completely missed the point of the NS conclusion. As iNow has pointed out the phrase is a call to readers of religiously oriented material, disguised as science, to read carefully to discover the true agenda of the writer. That seems both a wise and a 'scientific' thing to do. Now, in as much as you did not get this from the writing, maybe their editors need to a better job of getting an important message across. I think the storm over the NS cover article "Darwin was wrong" is relevant here. It generated a joint letter of condemnation from Dennet, Dawkins and others, as I recall. Doing my own reading between the lines I suggest NS may be taking the position that they will not needlessly dumb down any aspect of their treatment of evolution, or any other topic. Any bona fide scientist, or scientifically literate person, would take the title as a reflection of the errors in detail of Darwin's work. The decision with this - and with all pseudoscience - is whether or not to engage in debate over the material and the conclusions. I'm not voting either way (I'm a geologist: how could I be definitive?), but both approaches have pros and cons, so condemnation of either approach is unwarranted.

Petebro, I am going to echo the remarks of the other posters: what are you talking about? Specifically - 1) You imply that Darwin's theory of evolution by natural selection is a fringe theory. (... perhaps science may have shyed away from this area of research; we may vindicate Charles Darwin) Surely you realise that evolution lies at the heart of most biology research; that the basic concept is not questioned by any serious scientist. So what do you mean by these statements. I am greatly puzzled. 2) You imply that complex multicellular organisms may have evolved from simpler unicellular life. Why imply this when it is fully understood to be the case. You state "We maybe a long way from proving that lifeforms have evolved in a prolonged process of evolution." But we are not a long way from this. That has been well established for many, many decades. 3) You make several references to movement. You seem to attach particular importance to movement, however it is not clear to me why you think this is so important. Petebro, I don't wish to discourage you - and I worry that the responses to your post could be discouraging - but you seem unaware of the current status of Darwin's theory and the derivatives of it. I hope you can channel your obvious interest in this field into learning a little more about current ideas.

Are you OK so far? Sort of. Since it not's quite clear where you are going, I am having a little trouble following what precise meaning you are giving to your words - and that could make a difference. I am uncomfortable with your use of 'age'. It seems unnecessary. However, if I translate your title question to be "Is gravity an effect of how long something has been going on for?" then the answer is a definite No. Perhaps if you explain where you were headed with your question it will be easier to give a satisfactory answer.