Carrock

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Carrock last won the day on December 10 2018

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About Carrock

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    physics

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  1. If it's possible to get a loosely aggregated large icy body into low orbit, it might be possible to separate it with explosives into sufficiently small fragments to melt during entry. Any larger fragments could similarly be reduced in size. Very speculative idea, and even if it becomes possible, any miscalculation could be disastrous.
  2. Yours was a good response to my rubbish post. I misinterpreted the paper, the red mist descended and I pressed 'Submit Reply' without engaging brain...
  3. Carrock

    Strange light bulb behavior

    Old mains clocks, such as mathematic may have, had a synchronous motor and were dependent on mains frequency for accuracy. IIRC they had a tendency not to start, or to run backwards, so they were likely designed to work at lower than normal voltage, so that they'd be reliable at normal voltage. So the dimmed bulb may be normal, while the clock continued to run on a very low voltage.
  4. I realised I'd got it wrong, too late to edit my OP; I didn't make that clear enough. Or that I had realised is consistent with any valid QM interpretation. (The referenced book is behind a paywall; how 'environment' is defined is of course crucial.) Clarification: You appear to be referencing an unspecified paragraph from "Hawking, S. W. Particle creation by black holes. Commun. Math. Phys. 43, 199–220 (1975)." As I didn't quote from it, I don't think a cited reference has much relevance to the quality of the citing article. Don't know where you got that from... Congratulations on the cheerleading. +1 In summary: nothing in the paper appears to depend on a particular interpretation. I originally thought it did.
  5. I suppose on second thoughts that paper is a pretty normal Copenhagen interpretation; it's just the scale of the superposition that's unusual.
  6. From https://www.nature.com/articles/s41467-019-08426-4 Another quote from that paper: Ouch. From a reference from that paper: Joos, E. et al. Decoherence and the Appearance of a Classical World in Quantum Theory. (Springer, Berlin Heidelberg, 2003). So a whole paper with quantified maths about an arbitrary split between quantum superposition and a purely classical environment i.e. no superposition of different 'records.' This would only be valid if the Copenhagen interpretation was a distinct theory rather than an interpretation. Dubious theory isn't confined to SF speculation section...
  7. Carrock

    Assange! Free at last!

    The disinformation and ad hominem attacks go on.... Manning initially approached Assange. Whether Assange did anything more with Manning than most investigative journalists (not whistleblowers) would do is very questionable at present. The difficulty for the U.S. was/is finding a charge which would not also apply to a few million other journalists. The relatives of victims of the war crimes in Iraq and elsewhere who would otherwise never have known what happened likely have a different view on what is in the public interest than you do. Perhaps, like Hillary Clinton, you think the harm he did to the democrats outweighs this? Chelsea Manning was convicted and had her sentence commuted by Obama. She's now 'enjoying' her freedom during an indefinite prison sentence, much of her time in solitary confinement. A somewhat disproportionate sentence for an unnecessary witness? Secret justice is often more expedient than disappearing people.
  8. Carrock

    Favourite examples of good experimental technique

    Guess I'll denitpick by appealing to authority... I was told about the experiment; I don't recall doing it. And I didn't do the calculations so it still seems improbable. Sometimes ignorance is worth preserving. I'll keep my vestigial sense of awe unless (improbably) I have to learn the details.
  9. Carrock

    Favourite examples of good experimental technique

    One of my favourites is what used to be called the Millikan oil drop experiment. (It seems Fletcher's contribution was not acknowledged.) Measure the mass of a negatively charged oil drop by letting it fall at terminal velocity. Then calculate the charge from the electric field required to provide exactly the upward force required to balance the gravitational force. The calculated charge is always an integer multiple of the (now known) electron charge. Never having investigated the experiment, I still have some of my original awe that such a conceptually simple (in hindsight) experiment could measure something as tiny as the electron charge.
  10. Carrock

    Magnetar formed when two Neutron Stars merge:

    Interesting questions. Before reading the abstracts, I'd have assumed that e.g. two coalescing neutron stars each of 1.1 solar masses (apparently the minimum neutron star mass) would produce a neutron star of at most 2.2 solar masses and definitely not a BH. However, your first source hints that if the neutron-star equation of state is not sufficiently stiff transient high pressure may produce a region sufficiently large and dense in the coalescing neutron stars to form a black hole smaller than the usual minimum. AFAIK all the collisions observed so far have been binaries coalescing where much of the angular momentum ends up in the final neutron star/black hole e.g. one high spin magnetar. It's possible that collisions between non binary neutron stars etc are common enough for some to be observed eventually. Those seem to me, especially if the collision is nearly head on, to be the best option for producing unusually small black holes. Any other thoughts?
  11. Carrock

    Assange! Free at last!

    A few other points worth mentioning. From that reference The U.K. government is now considering a U.S. extradition request re computer hacking or similar. Maximum jail time would be five years, unless U.K. agrees to other charges after extradition, which is not unlikely. Chelsea Manning, having had her sentence commuted by Obama, is now back in jail for an indefinite time. It seems to have been almost forgotten that many instances of torture, murder of civilians and various other war crimes would likely have remained hidden without Manning and Assange. Possibly such crimes are now rarer because of Wikileaks. OTOH the U.S. has stated some people were put in danger by the leaks. There's a lot I don't like about Assange, but there is so much disinformation around that much of what I believe about him is likely wrong. (Even the BBC got the reason for extradition wrong.)
  12. 3 is definitely the most interesting, especially if they have the same problem when we try to explain e.g. how a bicycle works. BTW, I couldn't select the numbers in your post. Was that magic, or could I work how you did that if I really tried?
  13. Carrock

    Nerve Gear

    Even earlier computers...
  14. Carrock

    The concept of infinity

    As Wittgenstein might have said: Whereof one cannot speak without snark; one must thereof put a sock in it. I shall heed his advice. Uh ... which is it? Are there twice as many or the same as? Perhaps it's beyond YOUR comprehension. Damn, the snark leaked out anyway. Only happened because I read your post a second time and realized you yourself are fuzzy on the example. Did you read this earlier post, referenced in the post you quoted?[pedantic snark] Nothing in the rules against using onsite references.[/pedantic snark] Anything fuzzy here? The later post was inspired by a third party story of [appeal to authority] R. Feynman [/appeal to authority] showing a child 'there are more numbers than there are numbers.' I think children are as good as adults at learning something new, especially when, as I was careful to exemplify, they already have all the basic maths they need to understand a new concept. It takes a certain perverse sort of ignorance/laziness to teach children infinity is 'difficult,' compared to e.g. division.
  15. Carrock

    The concept of infinity

    Can you tell me which part of "infinity for five year olds," showing that there's twice as many integers as there are integers, or as many even numbers as integers or whatever, is beyond your comprehension? Or, as you likely meant, beyond the comprehension of a five year old?