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  1. J

    Animal Homing

    Excellent tip, thanks! It seems that this is an approved insulating method for roofs and walls in several countries. I would have to use it to seal the complete roof, which I am not qualified to do, so I will look for a contractor. I assume he will first have to remove all the tiles, so it will...
  2. J

    Animal Homing

    Yeah, and not only mice, Martens as well. Amazing that builders and roofers who live and work in the country don't seem to know these these things. Total incompetence that my roofer didn't give me access. Then he came afterwards and charged me for covering up a few holes he had left which I...
  3. J

    Animal Homing

    I agree that trapping and relocation is not a long term solution against animals which have a preference for living in roof spaces. My problem is compounded by the fact that I have no access to the interior of my roof as it is completely sealed, or so I thought. Apart from Martens I also have a...
  4. J

    Animal Homing

    Here is a study, but I don't have the full text. It does not say whether the maze was openair. This extract suggests to me that most cats do not use magnetoreception. There are a lot of anecdotal stories about long-distance cats (and other animals such as dogs), but it seems that most returning...
  5. J

    Animal Homing

    The 10 miles interests me. How did you decide this? How do you know it is far enough? What is your source? I am not familiar with problems associated with raccoons, but I think that they are nice animals and should be relocated if possible.
  6. J

    Animal Homing

    Thanks for the interesting article. It’s mainly about birds, which are mobile over a large area, can look down from a great height and can use airstreams to identify the source of odours. Land animals do not have these advantages. The article draws me to the conclusion that in the case of my...
  7. J

    Animal Homing

    I have been reading about the theory of magnetoreception which may partially explain the homing ability of pigeons. Many studies are inconclusive, so I am wondering if I can extend this theory to other animals, specifically to the Beech Marten (aka Stone or House Marten, Martes foina). This...
  8. J

    News "Women's March" around the world

    Well you have a family too, so what was his point? Unjustified discrimination can hold a company back and as an investor I am appalled at such a management attitude. Could it be that the other employee is overpaid? Huge inequalities of pay exist on the topside. In Europe we have massive...
  9. J

    IQ distribution curve

    So what do you think is the result in the world IQ distribution curve? Could it develop into a top-left declining to bottom-right curve with a shift of the mean to the left, instead of a bell? My interest in this thread is not to speculate, but to understand how evolution works in practice using...
  10. J

    IQ distribution curve

    I am using IQ as a proxy for general intelligence. There's no other way to do it, is there. I'm assuming that the general environment and intelligence level of African kids is on catchup, but Western intelligence levels have to increase too, don't they. So I'm wondering what evolution is likely...
  11. J

    IQ distribution curve

    I assume you mean that more kids in a family reduces nutrition and other disadvantages. I called this environment. So do you agree that we only have two factors - genetic and environment, and that the genetic difference is negligible?
  12. J

    IQ distribution curve

    Thanks for the link to the criticisms. I am not particularly interested in the book and I only mentioned it as a reference, as required in this forum, so that I could use the figures of 70 for average sub-Saharan Africa and 90 for world average IQ. Do you know of another source where I could get...
  13. J

    IQ distribution curve

    What does the distribution curve of IQ in the world population look like? If the average IQ for all countries is 90 (Richard Lynn and Tatu Vanhanen “IQ and the Wealth of Nations”), with an average IQ for sub-Saharan Africans of 70, I suppose that the distribution curve is higher on the downside...
  14. J

    B Can we identify the centre of the Universe?

    Just forget about the raisin-bread, which has a boundary. The Universe is everything, without a boundary, and the main constituent parts are seen to be moving away from each other with increasing velocity. In the beginning they were compactly close together, without any space between, but...
  15. J

    B Can we identify the centre of the Universe?

    How can dark energy remain at the same density when the space between the (super) clusters is increasing? I can think of three reasons: Dark energy is increasing in volume terms. Dark energy is decreasing, which takes up more space because it is negative. Emptiness is increasing. Which do...
  16. J

    B Can we identify the centre of the Universe?

    Glad it helps. I don’t like any of the analogies – Ballon, Fruit Bread, Donuts are all shown with 3D boundaries. Big Bang analogy is thought to be an explosion. That’s why there are all these questions about center of the universe and boundary. There is a lot of discussion about the observable...
  17. J

    News Should we stay in the EU?

    Yes, and what are the benefits – that is the question. The whole exercise has been started and is being run by academic dreamers and career bureaucrats in Brussels. They started with a common market, which is a great idea and is why the UK joined. Since then, they have extended it with a common...
  18. J

    Blue Disk illusion

    The orange disk remains stable, while the blue disk repeatedly (at about 1 to 2 second intervals) "tries" to recede. The article referenced by Vanadium 50 explains it. I haven't finished studying the article yet, but it says that some people do not see the receding effect. So as I understand it...
  19. J

    Blue Disk illusion

    The following picture has been posted in the Astronomy section (by Dave C426913). https://www.physicsforums.com/file:///C:/Users/John/AppData/Local/Temp/msohtml1/01/clip_image001.jpg [Broken] Source: http://www.space.com/4643-incredible-comet-bigger-sun.html Why does the comet fluctuate in...
  20. J

    Does a finite universe require 4 spatial dimensions?

    I appreciate this very interesting interpretation. Could you please clarify: You are talking about a single emission of light, but light is being emitted by galaxies everywhere in the whole universe. Are you assuming that there are no galaxies very far away from us, so that in that region no...
  21. J

    Duration of the Big Bang

    Correction: Decoupling occurred at about 380 thousand years after the BB.
  22. J

    Duration of the Big Bang

    This thread is getting like the BB. To answer your question, I would interpret the expansion of the universe as the dilation of space. So the universe is getting "bigger" in the sense of the increase of distances between galaxy super-clusters. (I choose super-clusters to be on the safe side...
  23. J

    Duration of the Big Bang

    Yes, I agree. But is our current definition of a second applicable at the BB event? I think not. Here we have to consider what time means. The best way of describing it which I have come across is that it relates to the passage of events. Without events there is no time. That is why time...
  24. J

    Duration of the Big Bang

    Thank you for the analogy, which has been quoted before. Some students have remarked that the 2D space analogy does not help them, and I also belong to this group. I prefer to discuss the 4D universe which we seem to live in. The OP asked about the timing of the BB and inflation and he later...
  25. J

    Duration of the Big Bang

    The idea of getting back to the starting point seems to be without foundation. It is not possible because the starting point would cease to exist and would not be discoverable. I am saying that I can go in one direction infinitely because I will never find a boundary. If the universe has no...
  26. J

    Duration of the Big Bang

    I am following the discussion with interest. Could someone please clarify what we mean by “infinite” in this context? Is it not so, that the universe is everything, in its broadest possible meaning, disregarding multiverses? In this case, the universe must be infinite and was always infinite...
  27. J

    Animal communication

    We are not discussing behaviour, we are discussing thinking and communication. Here is Pinker talking about it: https://www.youtube.com/watch?v=UZDeYe93rFg In this video he explains that thinking is independent of language. However, he does not go into the influence of language and other...
  28. J

    Animal communication

    I agree with you in parts. Since your OP was about animals, let’s take my dog again: First she sees the postman coming (sometimes I have the impression that she hears him loading the van in the village, but possibly her internal clock tells her that he is due to come). This is the sensory...
  29. J

    Animal communication

    Pointing does not always work well. For example, you pointed to me in your quote, which I did not write!
  30. J

    Animal communication

    Here is Chomsky talking about internal cognition and language. He agrees with me that the “externalization” (which I called signalling) is separate from our internal use of language. https://www.youtube.com/watch?v=6i_W6Afed2k It’s rather a long lecture and he gets off to a slow start, but worth...
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