Ophiolite

When I throw darts at a dartboard they form a triangle. Do you think the aliens have taken control of my motor functions?

The age of the Earth has been very clearly and accurately established through radioactive dating.[1] (Contrary to the deliberately ignorant views of Young Earth Creationists, those factors that can influence the apparent age of a sample are readily accounted for.) The oldest whole rocks dated on the Earth are currently thought to be part of the Isua Greenstone Belt in Greenland. These are dated at between 3.7 and 3.8 Ga. [2] However, there is active research in other Pre-Cambrian cratons and older candidates may appear. (The Accasta Gneiss, a terrane in Australia, and another Greenland greenstone belt are all possibilities. See here.) The oldest minerals on the planet are zircons from the Jack Hills in Australia. Zircons are very durable and these have been eroded from an igneous rock, then incorporated in a younger sediment. [3] The oldest of these zircons has been dated at 4.4 Ga. But these post-date the actual formation of the Earth through accretion from the protoplanetary disc in the young solar system. The age of the solar system is often taken to be the time at which the first solid particles formed. This is around 4.567 to 4.568 Ga. These and the later particles accreted to form the proto-planets and planets in a relatively short time - millions, of years, not many tens of millions. [4] If we date the formation of the Earth to the time of the giant impact that formed the moon, that would be around 30 million years after solar system formation. This is discussed, for example, by Jacobsen. [5]. The Earth has a radiogenic W-isotopic composition compared to chondrites, demonstrating that it formed while 182Hf (half-life 9 Myr) was extant in Earth and decaying to 182W. This implies that Earth underwent early and rapid accretion and core formation, with most of the accumulation occurring in ∼10 Myr, and concluding approximately 30 Myr after the origin of the Solar System. The Hf-W data for lunar samples can be reconciled with a major Moon-forming impact that terminated the terrestrial accretion process ∼30 Myr after the origin of the Solar System. Keep in mind that this is an active area of research and that ages will be refined, but we should not expect any significant deviations from these numbers. If the Earth was wholly molten at any point it cooled rapidly and a crust formed. (We call it a crust for a very good reason.) Thereafter surface temperature was maintained within a moderate range through the combination of solar radiation and the heat retaining properties of atmospheric gases. The contribution of heat from the interior of the Earth is miniscule in comparison. What part of this do you not understand or accept? The universe has no interest in your personal incredulity. References: 1. http://www.geo.cornell.edu/geology/clas ... ture04.pdf 2. Rollinson, H. The metamorphic history of the Isua Greenstone Belt, West Greenland Geological Society, London, Special Publications 2002 v. 199, p. 329-350 3. http://www.geology.wisc.edu/~valley/zir ... Nature.pdf 4. Krot, A.N. et al Origin and chronology of chondritic components: A review Geochimica et Cosmochimica Acta 73 (2009) 4963–4997 5. Jacobsen, S.B. THE Hf-W ISOTOPIC SYSTEM AND THE ORIGIN OF THE EARTH AND MOON Annual Review of Earth and Planetary Sciences Vol. 33: 531-570 May 2005

Recently I asked for support from the mod/admin team over systematic application of negative rep by a specific member. Rather than provide that support I was issued a warning by the team. My offense: calling the member an opinionated twat in my final pm to that member before putting them on Ignore. I joined the forum in 2004 while recuperating from a stroke. Thirteen years later I leave. It has brought me an immense amount of satisfaction, until now, to participate in it. My thanks to all of you whom I have interacted with. I shall no doubt miss you.

Please read the question Strange asked and try answering it, instead of the question you think he asked.

Well, I understood almost none of that, but I appreciate the reply. I shall spend some time looking up the terms you've mentioned, while trying to fight the natural indolence that has kept me from understanding physics until now. (I deny that it has anything to do with limits on my intellect.)

Last month I went to an excellent exhibition of Monet's paintings at the Museum of Fine Arts in Houston. The exhibition, Monet and the Seine: Impressions of a River, displayed over fifty of his works assembled from Museums in the USA and Europe, and from private collections. These include the Mornings on the Seine series, in which he captured the changing light through different stages of morning. He painted these on location, punting to his vantage point before dawn and moving from canvas to canvas through the day as the light changed. Anyone living in Texas and with an interest in art should grab this opportunity. The exhibition is on until February 1st.

Go read Life-line by Robert Heinlein. If the science won't convince you perhaps the fiction will.

Surely that is wholly contingent upon what the equation is and how accurately you want the answer.

Which makes Fermi's question, where is everybody, all the more compelling?

I'm sitting at my desk. Wait a moment. It's still there, even though this is many seconds later. It looks as if my desk exists in a time dimension as well as its three spatial dimensions. Who would have thought it?

I don't have any suggestions, but other members may be interested in this article from the BBC that describes the craze in Hungary for Escape Rooms. I think this is the sort of thing you are aiming for. http://www.bbc.co.uk/news/business-30415679

Two newly-wed neutrons walk into a bar and the bartender says, "I don't get it, what's the attraction?" Meanwhile, back on the ranch, it interesting that one of the principal axioms of science is that the physical constants are the same, not only over time, but in all parts of the universe as well. This has been questioned from time to time, tested - as far as it can be tested - and generally confirmed. Moreover, as I understand it, if it were not true many of our other observations would not be as they are, so many experiments incidentally confirm it. Now, taking a leaf from the book of the cranks and the woo-woo agents, I have a theory. Is their any chance that the red shift we attribute to expansion of the universe could be related to a systematic variation of one or other of the fundamental constants? I imagine this is either trivially ruled out, or was refuted by experiment long ago. I'm interested in knowing what rules it out. Can anyone explain to me, ideally in pop-science terms, with an equation or two thrown in, so I can pretend to be smart?

Another major difference between REM and non-REM sleep lies in the dreams associated with them. For most people the few dreams found in non-REM sleep tend to -have a rather thought-like character. During REM sleep, on the other hand, dreams occur more frequently and usually have a perceptual vividness and the illogical episodic character with which we are all familiar. From: Crick,F. & Mitcheson, G. The Function of Dream Sleep Nature Vol. 304 July 1983 To test whether mental activities collected from non-REM sleep are influenced by REM sleep, we suppressed REM sleep using clomipramine 50 mg (an antidepressant) or placebo in the evening, in a double blind cross-over design, in 11 healthy young men. Subjects were awakened every hour and asked about their mental activity. The marked (81%, range 39–98%) REM-sleep suppression induced by clomipramine did not substantially affect any aspects of dream recall (report length, complexity, bizarreness, pleasantness and self-perception of dream or thought-like mentation). Since long, complex and bizarre dreams persist even after suppressing REM sleep either partially or totally, it suggests that the generation of mental activity during sleep is independent of sleep stage. From: Oudiette, D. Dreaming without REM sleep Consciousness and Cognition Vol. 21-3 2012 And many hundreds more on Google Scholar.

As we all now know, it more like a box of chocolates.

Moderators: please allow the prior post to remain. It is pertinent to thread, since it demonstrates the point made by ajb that to understand something we must know the relevant vocabulary. Thus, my Russian was insufficient to understand the specific content. However, my familiarity with the formatting of spam and associated characteristics (members with a single post) allowed me to understand its nature in two seconds.

Which, neglecting air resistance, is exactly what you can do, as long as you do not accelerate, or decelerate the skateboard. The ball already possesses the same forward velocity as you. From your perspective the ball rises and falls vertically. To an observer, stationery on the sidewalk, it follows a parabola. If you wish it to rise vertically relative to the observer you will need to impart a backward velocity to the ball to counter your forward velocity.

Not nearly as offensive as The bullshit you have been posting Your aggressive attitude Your refusal to follow the forum rules and answer a question And now, your dishonesty in failing to leave the forum as you said you would Fortunately, I have an alternative to deal with point 4. You are now on Ignore. I must be getting old. I should have thought of that much earlier, but I actually thought you had come here to discuss things.

At no time have I insulted you. The only marginally inappropriate language is the use of frigging in my last post. Given your snide, refusal to adhere to forum rules, coupled with your cowardly withdrawal when things didn't go your way I find "frigging" to be quite mild. I find your suggestion that I might pursue you beyond the bounds of this forum to be grounds for a case of defamation of character. (Ask your father about that.) Now please honour what you claimed you were about to do and leave. Alternatively, answer the frigging question.

When did you first come to believe, mistakenly, that the thought experiment is what Einstein's conclusions rested on?

Absolutely not a fad. In fifteen years time its impact will be equivalent to the introduction of the mobile phone. Check back on this thread then to assess my prediction.

That's interesting John. Should I have known that from my chemistry in secondary school?

This sounds like a reasonable approach and I concede it may even be the right one. However, for me appropriate use of the word ignorance is in the same set as appropriate use of the word theory. If we have to dumb down our responses to the point that the language is in danger of being corrupted then we are failing in any duty we feel we have to educate.

Excellent. If you need any other hints just ask. It would be nice if you posted your solution once you've worked it out.

I can give you a long list of questions that are much dumber than that. However, this sounds very much like a homework question. We have a forum rule that we don't do homework for you, but we shall help you. 1. If the magnesium sulphate is dissolved in water, what ions will be present? 2. Which of these ions will be positive, which negative? 3. Is the cathode positive or negative? 4. Which will be attracted to it?

I'm sorry, but this is very frustrating. I do believe you are sincerely trying to communicate, but it is not working. It looks as if Strange and Acme are having similar problems. I don't think it is a problem of language. It seems more like a problem of following a logical train in your argument. For example, consider this. 1. You make a post that I do not understand. 2. I tell you I do not understand. 3. You tell me you have rephrased the words I did not understand. 3. I ask you where. 4. You point me to a post you made before the one I did not understand. 5. That cannot be a rephrasing of what you have said, unless you have a time machine. And, even having read that I still not any wiser. No, I just tried putting the two together, in different patterns, trying to find any meaning in them. I cannot. It does not make any sense to me at all.