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A Question from a Non Scientist

  1. Sep 27, 2005 #1
    Would one of the scientists here answer a question for me. If the Branes theory of many universes copes with the technical problems of the singularity via collisions, how does this do anything except transfer the philosophical problems from the singularity to the Branes? I am still asking what preceded the Branes and where did they come from.Can there be a dimension with nothing in it or with no properties. If not how did these characteristics arise? If time is a function of matter is it correct to say that there was nothing before the first existing property? If this is so then are all universes in fact eternal because all time is within them. I hope all you physicists will not mind being joined by a rather lowly philosopher.
     
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  3. Sep 27, 2005 #2

    selfAdjoint

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    Welcome to PF Daphne!

    Physiscists don't explicitly concern themselves with the philosophical consequences of their theories, although one might say they keep an eye cocked for them, and will expound them when coming to write popularizations. :wink:

    The tacit assumption of the colliding branes scenario is that the branes have "always" existed, and the collision is just one of an ongoing sequence of such events that has no beginning or end. Thus from a philosophical angle colliding branes gets us away from the "hard beginning" implicit in the big bang and back to a new form of the steady state cosmology.
     
  4. Sep 27, 2005 #3

    marcus

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    [EDIT: I see after posting that selfAdjoint has already responded in nice concise form. but I will leave this up anyway in case it sheds additional light]

    Daphne I think this thread would do better in philosophy forum and I hope it is moved there, because I think you are raising the question

    Where did it all come from?

    this is not a physics question, or strictly speaking even a scientific question

    In science the aim is to MODEL WHATEVER CAN BE OBSERVED in a way that assumes as little as possible and PREDICTS as much as possible, so that the model can be TESTED.

    A singularity just means a point or region where the model fails----where it starts to produce meaningless numbers or infinities. The vintage 1915 model spacetime fit the observations very nicely back to a moment where it failed and produced infinities. this was recognized as a sign something was wrong and it has been improved now so that it doesnt do that.

    Here is an sample from a modern theory (LQC) that removes the singularity:
    http://arxiv.org/abs/gr-qc/0509075
    Using the LQC model one can continue extrapolating time back PAST the place where the 1915 theory had a "big bang" singularity and into a prior contraction stage. The new model will have slightly different predictions about the microwave background, which are being worked out. This will allow it to be TESTED by looking for a kind signature or trace left over in the microwave background of expanded primordial light. Then if the LQC model does not check out it can be discarded and replaced with something better.

    BUT NO MATTER HOW GOOD THE MODEL GETS YOU CAN ALWAYS ASK WHERE DID IT ALL COME FROM because that is a philosophical or religious or literary or mythological question. The model is not supposed to give an answer to "where did it all come from" which is not a scientific question.

    What I am telling you is something out of philosophy of science. A cosmology model can be thought of as a machine which is consistent with past observations and predicts future observations (so that a wrong outcome can refute it) and the machine is not supposed to break down at some moment in the past, because that would be a glitch where it fails to apply, a limit on its applicability, a singularity. A breakdown at some past instant leaves a huge inelegant trash heap of explaining to do, like how did all these initial conditions get determined!

    Remember the game is to use the simplest assumptions and derive the most detailed and precise observations from them. To PREDICT THE MOST FROM THE LEAST.

    but even though you arrive at what is currently the simplest available most perfectly predictive model---- no matter how simple and elegant it is someone can still come along and ask "Where did it all come from?"-----and that simply moves the discussion out of the science department and into the realm of philosophy.
     
    Last edited: Sep 28, 2005
  5. Sep 27, 2005 #4

    marcus

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    WOW, great Jehosephat etc.
    it is highly providential that Daphne dropped in here because she could have been thinking that the cousins could use some of her experience with coping with religious issues in education in a civilized multifaith committee manner at the UK county level.

    As it happens we in USA are having a very unfortunate time of it just now because we have handled the business of the division of Church and State very poorly and alienated and radicalized a large segment of the cultural and religious Stay-puts who are now blockvoting against their own rational and economic selfinterest and supporting a cruel and stupid foreign adventure and it is simply destroying the USA and even somewhat the prior-established global system.

    This is tragic and it stems from issues connected to religious custom and doctrine. But look at THIS

    http://eastsussex.gov.uk/yourcouncil/about/committees/meetings/sacre.htm

    this is something which the UK people invented. If Daphne Bagshawe lives in UK then she probably can tell us about this. In particular if she lives in East Sussex. It is a COMMITTEE where you get all sorts of religious leaders (islam, baptist, quaker, buddhist, jewish, RC, Church of England, Russian orthodox you name it!) and get them together with COUNTY COUNCILMEMBERS and have a civilized conversation about how can we accomodate each other.

    Forget about the big bang, people! we are in an emergency where the religious right is destroying the country and we made a mistake somewhere along the way and brought this on. This is what the British are for they have ideas of how to deal with problems that we didnt think of and we should learn from them when we have difficulties.

    So please find the proper forum for Daphne (if she is knowledgeable about UK church/state institutions like this SACRE committee) and let us ask her questions!

    SACRE means "standing advisory council on religious education"

    sorry if this is just a "wild surmise" (a wild guess that D.B. is an east sussex yookay person) as in

    or like stout cortez when with eagle eyes
    he stared at the pacific, and all his men
    looked at each other with a *wild surmise*
    silent upon a peak in darien

    that kind of wild surmise (that DB was chairman of that committee until she stepped down, the minutes show, on 14 June 2004, heh heh must have left her with a lot of philosophico-scientific questions on her mind, if it is that DB)

    hello daphne, do you have any ideas? :smile:
     
    Last edited: Sep 28, 2005
  6. Sep 27, 2005 #5
    Hi Marcus Yes I was Chairman of our SACRE here in East Sussex where I was also Chairman of the whole Council but my question is not in my mind at any rate connected with that. I am very interested in modern Physics though I have no training in it. I try to understand what it is telling me about the nature of matter and time and I wondered how the new Branes analysis shed light on the start of our own Universe and then of course the start of everything else. I am grateful for the replies and am mulling them over. Thanks for replying. I do not assume that our experience in the UK would be useful in the US but of course I would be very happy to explain how our SACRES work and what they achieve over here
     
  7. Sep 27, 2005 #6

    marcus

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    thanks for replying to my somewhat disorderly and clamorous post, Daphne. I was uncontrollably excited at the moment, when it occurred to me that UK might have invented an institution to help diverse religious groups be comfortable with science education. a sore point. almost a kind of vendetta against darwin going on.

    However given that your expressed concern is with physics, and cosmology in particular, we should put the SACRE discussion on hold and address your questions.

    I will try to help. selfAdjoint, who is knowledgeable and courteous, will certainly be back. we may get help from quite a few other people---I hope to your eventual satisfaction
     
  8. Sep 27, 2005 #7

    marcus

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    In the meantime, until selfAdjoint gets back and can describe the brane scenarios, won't you have a look at these two papers

    http://arxiv.org/hep-th/0505154
    Reconstructing the Universe

    http://arxiv.org/hep-th/0509010
    The Universe from Scratch

    just click on "PDF" to get a download of the whole paper, and flip through to see if there are any pictures. just read the first paragraph of the introduction and glance at the conclusions. to get an idea

    this is the socalled CDT model. a rival to branes, and to LQC
    you should get to know all three, not just branes
    people are getting good at modeling the emergence of spacetime
    it is actually exciting, there are new ideas taking shape
     
  9. Sep 27, 2005 #8

    selfAdjoint

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    Here is a pretty good resource on one of the colliding brane models (there are several). It's from a talk given last year, so it's fairly up-to-date: http://www.arxiv.org/abs/astro-ph/0401579 The way to see the full text is just the same as for Marcus' CDT citations, the link takes you to the abstract and you click on PDF (assuming you have a reader for that).

    Here are a couple of quotations from the paper to give the flavor. The word alternate in the first one refers to big bang/inflation cosmology. The singularity referred to in the second quotation is not the big bang, but rather the singular physics where/when the branes collide. The various references in brackets are available from the full text; many of them are links if you want to follow up.


    and

    So you see they assume recurring collision events within a continuous time frame.
     
    Last edited: Sep 27, 2005
  10. Sep 27, 2005 #9

    marcus

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    Daphne, people here, myself included, can also provide simplified paraphrase. We just have to understand what level works for you, which can take some trial and error.

    Ask repeatedly to have stuff explained, as required.

    To reinforce what sA just said, it is also good to have at least some minimal exposure to original sources----journal articles. If you can scan them to find comprehensible passages, and avoid getting bogged down, you will get some firsthand impressions and that way not be wholly dependent on popularized accounts.
     
    Last edited: Sep 27, 2005
  11. Sep 27, 2005 #10
    I thought that observations of background radiation showed the universe was probably flat and open, no big crunch. Was that an overstated conclusion that has since been refuted?
     
  12. Sep 27, 2005 #11
    Hi Daphne

    A cynical point about clashing branes scenarios - string theorists are desparate for testable theories at the moment and so unlikely stories get promoted on the grounds that they are at least testable. It is a way of keeping funding rolling.

    On your more general point, you will find that physicists are indeed fairly myopic about the metaphysics of what they are doing. Marcus expresses the epistemological orthodoxy.

    If you study epistemology, you will recognise a reasonably clear division between science as philosophy (truth models) vs science as technology (control models). Most scientists are a little confused as to which they are doing, and some even think the two styles of modelling are the same!

    If you are seeking a different metaphysical slant to the conventional reductionist/atomist equation of getting something from nothing, you can consider the alternative based on the notion of ontic vagueness - getting crisper somethings as a development or phase transition from vaguer states of potential. A potential is a realm where everything is possible, even if nothing has actually happened. In physical terms, you might be talking about spacetime fluctuations over every scale - a chaos of dimensionality. Then via a phase transition or symmetry breaking you would have this disoriented realm line up to make a smoothly coherent system. You would get a crisper something from a vaguer everything.

    Time would be also vaguer in the "prior" vagueness. So there would be "time", but not as we know it Jim - a smooth progressive flow.

    To make sense of this approach, you have to have some model for how a system can self-organise out of a vague chaos. Here you can tap into dissipative structure theory, or pan-semiotics, or scalar hierarchy theory, or some of the other interesting approaches available in complexity science.
     
  13. Sep 27, 2005 #12

    marcus

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    Dear Daphne, as distinguished visitor you honor us by your question. Please do not be dismayed if you hear shouting.

    BTW I was trained as mathematician, not physicist, so cannot call myself a scientist but nevertheless beg your indulgence to reply to the question, as one who, in his retirement, took up with the quantum physics of spacetime ("quantum gravity" for short since gravity is the geometry of spacetime).

    If the Branes theory of many universes copes with the technical problems of the singularity via collisions, how does this do anything except transfer the philosophical problems from the singularity to the Branes?

    I do not think brane-cosmology copes especially well with the singularities of the classical theory, or with anything else----am inclined rather to view it as a passing fashion. But IF IT DID cope in a creditable way then indeed IT WOULD "transfer the philosophical problems from the singularity to the Branes."

    One does not need such an elaborate set-up as extra dimensions with loose branes bumping----if one wants to cure the classical singularities by quantizing the classical (1915) theory.

    This is one of the main points being made at next month's Loops 05 conference at Potsdam outside Berlin----October 10-14.
    http://loops05.aei.mpg.de/
    Pretty much the whole of Friday is devoted to talks about LQC removing the singularities of classical cosmology. It does so without having to assume any extra dimensions

    Occam's razor. (Dimensions, and other) entities are not to be multiplied unless necessary.

    My guess is that brane-cosmology will dissipate with time. Actual working cosmologists, judging by the papers on file at arxiv.org, are not much interested in brane models.

    If you wish, have a look at the Loops 05 conference programme
    http://loops05.aei.mpg.de/index_files/Programme.html

    If you look at Friday you see Roy Maartens of University of Portsmouth talks at 12:20, followed by Abhay Ashtekar of Penn State and from then on it is all cosmology, and testing loop cosmology, and removing the classical singularities etc. for the rest of the day.

    Loop quantum cosmology (LQC) is undergoing rapid growth, people are entering the field and the number of papers per year is increasing.

    On the other hand the number of papers mentioning "brane" in the abstract has been declining from 2001 to present. One can easily check this with the Harvard abstracts search engine. I would not venture to interpret this but the decline in the number of brane papers per year is fairly clear.

    So you could modify your question and bring it more up to date by recasting it:
    "If the LQC theory of copes with the former classical singularity by getting rid of it and extrapolating time back to an earlier contracting phase, how does this do anything except transfer the philosophical problems from the singularity to the LQC model itself?"

    And I think that philosophically it does NOT do much else. If you were to ask that rhetorically I would have to immediately agree with you. If you said "It doesnt solve any philosophical problems at all, does it? It just gives them a different technical shape and setting." I would have to say "Right."

    But IMO the model is not intended to solve philosophical problems. Rather it is supposed to be simple (which LQC is rather) and to fit the data and to make predictions about future observations so it can be tested. That it seems to do or to be in the process of doing. Roy Maartens would be one to ask about that, he devises ways of TESTING theories and he has worked both with branes and with LQC. He is not committed to one quantum cosmology or another, that is not his line, he is more the pragmatic "phenomenologist" type. Also he nags theorists to make testable predictions (nagging is also a phenomenologist's privilege and duty) and checks their sums.

    In fact a way to get a good unbiased report on all this would be to telephone Prof. Maartens, since you are in UK.
    An academic should listen to an East Sussex Councilor. By jove, I will get you his email too, if I can find it. Then you shall have all this from the horse's mouth. But write him before he leaves for Germany to give his talk.

    this is a list of all Prof. Maarten's papers since the arxiv began
    http://www.arxiv.org/find/grp_physics/1/au:+Maartens_R/0/1/0/all/0/1
    there are 95 in all, on the arxiv. (before 1992 preprints were not archived electronically). You can see many many about branes. but lately quite a few about LQC.

    here is his Uni Portsmouth page with photo (to recognize him on chance encounter) and email
    http://www.tech.port.ac.uk/staff/index.php?id=125
    http://www.tech.port.ac.uk/staffweb/maartenr/

    South African, PhD 1980. here is the abstract of the invited talk he is to give at the conference Friday 14 October:

    Speaker: Prof. Roy Maartens
    Title: COSMOLOGY AND QUANTUM GRAVITY
    Abstract: I will review the basic features of the standard, classical model of cosmology, which is based on General Relativity, and how this model accounts for observed properties of the universe. Modifications to General Relativity that are inspired by quantum gravity need to be tested against cosmological observations. This is one of the key tests for any candidate quantum gravity theory. I will discuss in general terms some of the difficulties involved in this aim, and what is needed from theorists in order to achieve this aim. In particular, I will compare some of the features of stringy cosmology and loop quantum cosmology.
     
    Last edited: Sep 27, 2005
  14. Sep 27, 2005 #13

    marcus

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    Geeze, looks like Daphne lives some 50 miles from Portsmouth and she is asking about quantum cosmology models like brane (and should also be considering Loop) and the little-known world authority on comparing and testing these quantum cosmology models is living 50 miles away. Like, hey Daphne, drive over and have lunch.

    But on what pretext? She doesnt know enough yet to converse with the guy. Unless he is a natural-born pedant and loves explaining.

    East Sussex is where the normans landed, if I remember. unless I'm mistaking it for somewhere else, Kipling wrote a little book about the area and its history.
     
  15. Sep 28, 2005 #14
    Thanks from a non scientist

    Thanks to everyone who has tried to help me understand some of these current hot topics. As I am not a scientist it will take me some time to absorb information from the various original papers recommended but I am going to have a go and when I have done so I will come back to the board. Meanwhile a couple of comments on what you have variously said so far. I do now more clearly understand the distinction between the observe and predict science and the observe and explain science .It occurs to me that predictive verification could be a chimera in that it does not of itself guarantee an explanation.The ancients who thought the Sun rolled across the sky in a chariot were correctly able to predict its return but their explanation of the phenomenon was false.I am surprised at the consensus that "where did it all come from " is not a Scientific question. If it could be shown that matter could suddenly arise in a vacuum for example , then the question would be answered by a proof that things do not have to come FROM anywhere.Although I am delighted to discover I live close to one of the leading figures in this field I do not think I understand enough about the subject yet to justify taking up his time but I'm working on it.! Finally I am aware how justifiably depressed many scientists are at what they see as the rejection of rational scientific discovery by religious people.In my view all religious people should listen and learn from scientists. You folk are describing and explaining how things ARE.How can that be anything other than beneficial ? I admire you all very much. Best wishes Daphne
     
  16. Sep 28, 2005 #15

    selfAdjoint

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    Thank YOU for that most intelligent response. The problem with "why" questions is that you get into philosophical trouble. As Aristotle pointed out, either you have an infinite regress of causes or you have a first cause. And as Kant pointed out, both the statement that causes go back forever and the statment that there was an uncaused caused are incoherent - we can't handle them rationally.
     
  17. Sep 28, 2005 #16

    Chronos

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    Indeed, SA has captured the whole dilemma in a nutshell. Questions like 'How did the universe originate' do not lend themselves to the scientific method. In science you must quantify your answer for it to be meaningful. How do you identify and quantify the factors necessary to predict the emergence of the universe?
     
  18. Sep 28, 2005 #17

    marcus

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    Daphne has just passed thru this farflung outpost and reviewed the troops, gentlemen, and we have received her commendation.

    BTW has anyone read Kipling's little book about East Sussex, the area around Pevensey Bay (where norman landed). It is called Puck of Pook's Hill and nominally for children.

    Now that Daphne has graciously achieved closure on her initial segment of this thread, and appears to have returned to East Sussex County Council business, and to her Life, we can all kick off our loafers and relax. Of course we all KNOW how the universe arose---it grew out of Shiva's navel---but we can't say this in front of Daphne because that wouldnt be scientific and we are supposed to talk like proper scientists.

    Yes the details are that Shiva was asleep on a 7 headed cobra that was floating on the timeless infinite ocean. And as he slept a lotus grew out of his navel. And a little head poked up out of the lotus---it was Brahma! And Brahma thought it would be nice to have universe for his and Shiva's amusement, so he created the whole universe!

    And Shiva and Brahma are to enjoy the universe for 50 billion years (called a kalpa or the Day of Brahma) and then it all goes back into Shiva's navel and he sleeps for another 50 billion years (called the Night of Brahma) and then it starts over.

    And we aren't even in the first cycle. I forget what cycle we are in already.
     
    Last edited: Sep 28, 2005
  19. Sep 28, 2005 #18
    So I guess all this speculation about first principles is really no more than what I tell waitresses about why I am studying geometry....it keeps the Alzheimers (pronounced "Old Timer's) disease away. As we used to say in the Infantry, stay alert, stay alive. I don't recall anyone ever asking why about that.

    In another close encounter of the restaurant kind, I once had a conversation with a passing lesbian who told me she was thinking of switching. I wasn't able to be of any assistance there. So we talked about physics, among other things. I explained my big T.O.E., and she asked me if it was any good for making weapons. I said I didn't think so. Too bad, she said. Turned out I wasn't much use to her at all, but we had a nice talk.

    The Shiva story is warm and clever and makes us all feel as pleasent as eating lotus root. But it isn't really of any use to anyone, except to show the futility of thinking about it. I still prefer to delude myself into thinking we can do better than that.

    So far, the only really interesting thought I have had about fractals in regard to CDT has been that we see fractals at all scales, so what is special about the appearance of fractals at very short length scales? I presume that there really is something interesting about fractal geometry at very short length scales, but I still don't know what it is. Only the general idea of receeding self-similar lotus petals at the heart of everything does seem to take some of the nerve out of the singularity question.

    Maybe it will be useful sometime to have a device capable of erasing this quarter of the galaxy, I don't know. I have no need for that much power today and doubt I would be comfortable having it in the hands of our present governments....any of them. Still, when cutting firewood I do long for anti-gravity or at least a sky-hook or something to make carrying it easier. And .99c travel could be quite interesting. I should think I would like to find out if the universe is infinitely random or if it repeats itself from time to time. I wonder if it ever begins to drool and mumble as it tells the same old stories to itself, over and over.

    Meanwhile I think I have found an error in Barnsley's pedagogy. It is too complicated to present here and I am full of self doubt. Maybe it just looks like an error because I still don't really know how to read his notation. In short he says that if A,B, and C are sets in a Hausdorff space, and B is a subset of C, then the distance from A to C is always less than or equal to the distance from A to B. But this does not seem to me to be true if A is a subset of B or of C. I think maybe he was neglecting that possibility.

    I noticed no one mentioned black hole evaporation in response to Daphne's question about something from nothing.

    Well, I have an invitation for after-dinner conversation over vats of pickled beets and canning jars, so I'll end here. It is supposed to freeze for sure tonight, and all my neighbors are working with their produce. Maybe I'll put in a garden next year.

    Be well,

    Richard
     
  20. Sep 28, 2005 #19

    marcus

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    Richard if A is a subset of C then the distance from
    A to C is zero, is it not?

    and zero is less than or equal to any other distance including that from A to B (which could also be zero and that wouldnt hurt)

    Ah, but I see you are busy pickling beets, so i will not get your attention for a while.

    so I think perhaps the author has not made a mistake after all
     
    Last edited: Sep 28, 2005
  21. Sep 28, 2005 #20

    marcus

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    Richard spacetime may well be fractals all the way down, as follows


    if CDT is right then the microscopic spacetime structure is tree-like, branchy
    (and only to us crude macro-animals looks 4D at large scale)

    But if LQG is right (also) then at very large scale OUR UNIVERSE BRANCHES and is part of a treelike structure, because every black hole connects to a new big bang and a new future, that goes "out the bottom" and so TIME FORKS in a very forky way because one tract of universe like ours can have thousands of black holes and thus thousands of forkpoints.

    so OUR SPACETIME IS AT VERY LARGE SCALE A FORKY THING that could be the microscopic structure of somebody else's spacetime one level up and his would again look 4D because he is a crude creature analogous to us.

    and HIS universe could be doing the same Hole-Bang connection and creating its own branchy structure which could be the microscopic basis for yet another layer

    And if layers can build up, turtle upon turtle, then they be imagined descending turtle beneath turtle. and so whoever it was who said it may have been right, that it is turtles all the way (up as well as) down.

    or fractals if you like
     
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