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  1. #1
    Thailand Expat tomcat's Avatar
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    Universe: no beginning?

    ...consideration of an unanswerable topic for a longer Sunday read:

    Physicists Debate Hawking’s Idea That the Universe Had No Beginning
    by Natalie Wachover (Bloomberg)


    In 1981, many of the world’s leading cosmologists gathered at the Pontifical Academy of Sciences, a vestige of the coupled lineages of science and theology located in an elegant villa in the gardens of the Vatican. Stephen Hawking chose the august setting to present what he would later regard as his most important idea: a proposal about how the universe could have arisen from nothing.

    Before Hawking’s talk, all cosmological origin stories, scientific or theological, had invited the rejoinder, “What happened before that?” The Big Bang theory, for instance — pioneered 50 years before Hawking’s lecture by the Belgian physicist and Catholic priest Georges Lemaître, who later served as president of the Vatican’s academy of sciences — rewinds the expansion of the universe back to a hot, dense bundle of energy. But where did the initial energy come from?

    The Big Bang theory had other problems. Physicists understood that an expanding bundle of energy would grow into a crumpled mess rather than the huge, smooth cosmos that modern astronomers observe. In 1980, the year before Hawking’s talk, the cosmologist Alan Guth realized that the Big Bang’s problems could be fixed with an add-on: an initial, exponential growth spurt known as cosmic inflation, which would have rendered the universe huge, smooth and flat before gravity had a chance to wreck it. Inflation quickly became the leading theory of our cosmic origins. Yet the issue of initial conditions remained: What was the source of the minuscule patch that allegedly ballooned into our cosmos, and of the potential energy that inflated it?
    Asking what came before the Big Bang … would be like asking what lies south of the South Pole.

    Hawking, in his brilliance, saw a way to end the interminable groping backward in time: He proposed that there’s no end, or beginning, at all. According to the record of the Vatican conference, the Cambridge physicist, then 39 and still able to speak with his own voice, told the crowd, “There ought to be something very special about the boundary conditions of the universe, and what can be more special than the condition that there is no boundary?”

    The “no-boundary proposal,” which Hawking and his frequent collaborator, James Hartle, fully formulated in a 1983 paper, envisions the cosmos having the shape of a shuttlecock. Just as a shuttlecock has a diameter of zero at its bottommost point and gradually widens on the way up, the universe, according to the no-boundary proposal, smoothly expanded from a point of zero size. Hartle and Hawking derived a formula describing the whole shuttlecock — the so-called “wave function of the universe” that encompasses the entire past, present and future at once — making moot all contemplation of seeds of creation, a creator, or any transition from a time before.

    “Asking what came before the Big Bang is meaningless, according to the no-boundary proposal, because there is no notion of time available to refer to,” Hawking said in another lecture at the Pontifical Academy in 2016, a year and a half before his death. “It would be like asking what lies south of the South Pole.”




    Stephen Hawking and James Hartle at a 2014 workshop near Hereford, England.
    Cathy Page

    Hartle and Hawking’s proposal radically reconceptualized time. Each moment in the universe becomes a cross-section of the shuttlecock; while we perceive the universe as expanding and evolving from one moment to the next, time really consists of correlations between the universe’s size in each cross-section and other properties — particularly its entropy, or disorder. Entropy increases from the cork to the feathers, aiming an emergent arrow of time. Near the shuttlecock’s rounded-off bottom, though, the correlations are less reliable; time ceases to exist and is replaced by pure space. As Hartle, now 79 and a professor at the University of California, Santa Barbara, explained it by phone recently, “We didn’t have birds in the very early universe; we have birds later on. … We didn’t have time in the early universe, but we have time later on.”

    The no-boundary proposal has fascinated and inspired physicists for nearly four decades. “It’s a stunningly beautiful and provocative idea,” said Neil Turok, a cosmologist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, and a former collaborator of Hawking’s. The proposal represented a first guess at the quantum description of the cosmos — the wave function of the universe. Soon an entire field, quantum cosmology, sprang up as researchers devised alternative ideas about how the universe could have come from nothing, analyzed the theories’ various predictions and ways to test them, and interpreted their philosophical meaning. The no-boundary wave function, according to Hartle, “was in some ways the simplest possible proposal for that.”

    But two years ago, a paper by Turok, Job Feldbrugge of the Perimeter Institute, and Jean-Luc Lehners of the Max Planck Institute for Gravitational Physics in Germany called the Hartle-Hawking proposal into question. The proposal is, of course, only viable if a universe that curves out of a dimensionless point in the way Hartle and Hawking imagined naturally grows into a universe like ours. Hawking and Hartle argued that indeed it would — that universes with no boundaries will tend to be huge, breathtakingly smooth, impressively flat, and expanding, just like the actual cosmos. “The trouble with Stephen and Jim’s approach is it was ambiguous,” Turok said — “deeply ambiguous.”
    Murray Gell-Mann used to ask me, ‘If you know the wave function of the universe, why aren’t you rich?’

    In their 2017 paper, published in Physical Review Letters, Turok and his co-authors approached Hartle and Hawking’s no-boundary proposal with new mathematical techniques that, in their view, make its predictions much more concrete than before. “We discovered that it just failed miserably,” Turok said. “It was just not possible quantum mechanically for a universe to start in the way they imagined.” The trio checked their math and queried their underlying assumptions before going public, but “unfortunately,” Turok said, “it just seemed to be inescapable that the Hartle-Hawking proposal was a disaster.”

    The paper ignited a controversy. Other experts mounted a vigorous defense of the no-boundary idea and a rebuttal of Turok and colleagues’ reasoning. “We disagree with his technical arguments,” said Thomas Hertog, a physicist at the Catholic University of Leuven in Belgium who closely collaborated with Hawking for the last 20 years of the latter’s life. “But more fundamentally, we disagree also with his definition, his framework, his choice of principles. And that’s the more interesting discussion.”
    After two years of sparring, the groups have traced their technical disagreement to differing beliefs about how nature works. The heated — yet friendly — debate has helped firm up the idea that most tickled Hawking’s fancy. Even critics of his and Hartle’s specific formula, including Turok and Lehners, are crafting competing quantum-cosmological models that try to avoid the alleged pitfalls of the original while maintaining its boundless allure.

    ...remainder of the article here: https://www.quantamagazine.org/physi...ning-20190606/
    Last edited by tomcat; 09-06-2019 at 07:42 AM.
    Majestically enthroned amid the vulgar herd

  2. #2
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    YourDaddy's Avatar
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    I still think that universe is a giant zit on someone's ass and when that zip pops so will the universe.

  3. #3
    Thailand Expat tomcat's Avatar
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    Quote Originally Posted by YourDaddy View Post
    a giant zit on someone's ass
    ...anyone we know?...

  4. #4
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    Cyrille.....

    A textbook definition of multiverse

  5. #5
    Thailand Expat tomcat's Avatar
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    Quote Originally Posted by YourDaddy View Post
    Cyrille.....
    ...do you have a backup?...

  6. #6
    Balls to Monty
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    I have just finished listening to A Universe from Nothing by Lawrence Krauss audiobook.

    Very sharp and concise explanation from a great contemporary cosmologist of how a universe can come to exist from nothing. The fact that the big bang happened and resulted in a universe of unimaginable size and containing unimaginable amounts of stuff from nowhere and nothing is not the inexplicable miracle that it would at first seem given that the total energy balance of entire universe is exactly zero.

    Always fun to see the scientists forcing god to retreat further into the painted corner.

    I had listened to about half the length of the book before a chapter repeat alerted me to the fact that I had my player on 'shuffle' and had been listening to the chapters in a random order.

    I then listened to the whole thing from scratch in sequence so I have heard half the chapters twice now.

    There are 2 possible explanations as to why I had not noticed the shuffle randomness.

    1. I have already watched and read extensive teachings on cosmology so there is not much in this concise summary text that I have not heard before.

    2. My small monkey brain was so dwarfed by the scale and grandeur of the subject that it did not have sufficient perspective to notice the out of sequence nature of the material

    I am going with explanation 1 for the time being but 2 remains a distinct possibility.

  7. #7
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    Creatures residing on a photon wondering where the burst of light, their photon is part of, comes from,
    Wouldn't it be funny if the burst of light was simply one burst of many from a strobe light, and the strobe light was only a small part of a discotech?
    The sooner you fall behind, the more time you have to catch up.

  8. #8
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    Quote Originally Posted by tomcat View Post
    ‘If you know the wave function of the universe, why aren’t you rich?’

    The wave function of the Universe is 42.

    Where do I pick up my check?

  9. #9
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    there is an excellent BBC documentary about vaccum and how it can create particles out of nowhere and we don't why, and could be the explanation behind it all why the 'vaccum' is expending and what was happening before the big bang that is now believed not to be the actual beginning of the universe

  10. #10
    Days Work Done! Norton's Avatar
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    Quote Originally Posted by Dragonfly View Post
    vaccum and how it can create particles out of nowhere and we don't why
    If the vacuum is between the ears we know why.

    http://teakdoor.com/speakers-corner/...-still-on.html (Brexit - It's Still On!)

  11. #11
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    I don't like the big bang theory much or the idea that there was nothing and then something, not do I like the cosmic inflation trickery.

    I quite like the idea that we are inside a black hole though. That's quite cool thinking and doesn't need any kick-starts.

  12. #12
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    the thais have got it all figured out with their theory of "don tink two mat".

  13. #13
    ความรู้ลึกลับ HuangLao's Avatar
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    A proposed and narrow species-centred perspective will always lessen the learning curve.

    And still, we don't get it.
    The continued existence of absolutes.

  14. #14
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    Quote Originally Posted by Norton View Post
    told you all along that Brexit was a big fuckup, you thought REF2 or GE was going to happen

    DO NOT TEST MY VACCUUM ABILITY !!!

  15. #15
    Thailand Expat jabir's Avatar
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    Big bang cannot be credible as a one-off. If the uni is 13.5bn years old and continues to expand another x bn years then slows down over more billions of years before grinding to a halt and then contracting, the end result (sic) must be another big bang.

    If this theory describes how our universe actually came to be then it must be just the most recent of quite big repetitive expansion/contraction events stretching back into times beyond our concept or imagination, all the way back to infinity.

    Talk of time and we tend to think of infinity as being so far ahead that it could never be reached. But there's no reason why it cannot be behind us instead of or also ahead, so that there must have been an infinite number of universes created by big bangs, and now I need to lie down.

  16. #16
    Thailand Expat cyrille's Avatar
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    Quote Originally Posted by jabir View Post
    If the uni is 13.5bn years old


    ffs

    There's someone who didn't make it to uni.

  17. #17
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    Quote Originally Posted by jabir View Post
    If this theory describes how our universe actually came to be then it must be just the most recent of quite big repetitive expansion/contraction events stretching back into times beyond our concept or imagination, all the way back to infinity.
    It was open for a long time. We did not know if expansion would go on forever or reverses to contractions at some time. With the recent findings we now know expansion is actually increasing, pointing at dark energy. There is not going to be a big crunch.

  18. #18
    'ello 'ello 'ello Luigi's Avatar
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    Quote Originally Posted by Troy View Post
    I don't like the big bang theory much or the idea that there was nothing and then something,
    Though, with an observable universe full of 'things' right in front of our telescopes, at some point there was nothing, and there was quite a lot of 'something'. Be it after the Big Bang or before, in another theory.


    The Big Bang is pretty obvious, though the term 'Big Bang' came about as a derogatory joke on the people that first proposed it, whether that inflation was the beginning of Space-Time, or simply the birth of our universe in either a multi-verse or procession of universes that inflate or contract is probably 50/50.

  19. #19
    Thailand Expat tomcat's Avatar
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    Quote Originally Posted by Luigi View Post
    at some point there was nothing, and there was quite a lot of 'something'
    ...which brings to mind another question: is the amount of matter in the universe finite?...what about the amount of matter outside the universe?...

  20. #20
    'ello 'ello 'ello Luigi's Avatar
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    Quote Originally Posted by tomcat View Post
    outside the universe
    ..titillating viewpoint...

  21. #21
    Days Work Done! Norton's Avatar
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    In the begining there was nothing but darkness then the Lord said let there be light and Christ you could see for miles.

    All right there in the good book. You guys tink too mut.

  22. #22
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    it's amazing how the old testament is describing things that we are only explaining now scientifically

    maybe the old testament was written by our space alien ancestors

  23. #23
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    Quote Originally Posted by Norton View Post
    In the begining there was nothing but darkness then the Lord said let there be light and Christ you could see for miles.

    All right there in the good book. You guys tink too mut.

    the first book of science was actually the old testament,

  24. #24
    Thailand Expat jabir's Avatar
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    Quote Originally Posted by Takeovers View Post
    It was open for a long time. We did not know if expansion would go on forever or reverses to contractions at some time. With the recent findings we now know expansion is actually increasing, pointing at dark energy. There is not going to be a big crunch.
    Er, if expansion is increasing does that mean it will continue increasing forever? Which 'theory' is it that says added momentum after 13.5bn years means it will never slow down, eventually stop and then reverse?

  25. #25
    Thailand Expat jabir's Avatar
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    Quote Originally Posted by squirrel View Post


    ffs

    There's someone who didn't make it to uni.
    Hi squirrel, guessed you'd turn up like a lethal fart. Poor thing, what's your problem this time?

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