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The Fabric of the Cosmos 344

Genady writes "It's about time. Ever since I picked up a copy of Julian Barbour's The End of Time I've been intrigued by time. Everyone understands the concept of time to some degree, yet to explain why time is, is a mental puzzle that has played in the outskirts of my mind for years now. Brian Greene, author of The Elegant Universe has brought us a compelling, easy-to-follow journey through the history of physics and beyond to tackle the very question of 'why is time?' and 'what is space'?" Read on for the rest of Genady's review.
The Fabric of the Cosmos
author Brian Greene
pages 576
publisher Knopf
rating 7
reviewer Genady
ISBN 0375412883
summary A capsule review of current conceptions of the world of space and time, and enough background for laymen to understand how they came to be.

Now, when I say "easy," this is, like so much of Greene's book, relative. It's taken me three weeks to wade through the concepts and often humorous prose that goes along with them. Being something of a physics geek, I have a basic concept of relativity and quantum mechanics. Greene takes his time laying out classical physics, from Newton to Einstein, exploring the version of the universe presented by the laws of the very large. He then dedicates just as much room enumerating the precepts of the standard model as well as those of quantum mechanics. With these two pillars of modern physics established, we are next whisked on a journey through cosmology, delving further and further back into the history of the universe until both quantum mechanics and relativity break down and we are introduced to strings.

Greene's attention to strings does not overwhelm the book, as in The Elegant Universe, and he doesn't delve deeply into the concepts and math behind any of the theories of physics as in the latter half of his earlier text. What he does present is a very good conceptual overview of modern physics, all the while using the frameworks provided to drive at the central question: What are space and time? (Or "spacetime" as relativity puts it).

This sophomore effort is actually better, I believe, than The Elegant Universe. Greene has a way of explaining things in terms that non-physicists can grasp. His use of pop-culture icons to drive his points home are as masterful as they are funny. It would be my bet that should this book be made into its own television special (and it should) it will have to be a joint work by PBS and Fox. After seeing Greene present his Elegant Universe on PBS, and reading this book, I'm beginning to see him as a new Carl Sagan, or perhaps the illegitimate love child of Sagan and Matt Groening, if such a thing were possible.

In the end, though, the book has left me with more questions than answers. To be sure, Greene and the theories that he covers provide answers, but to conceptualize and understand them is my current difficulty. I'm sure that some of my own problems arise from learning through allegory. Not having the mathematical background to understand these concepts on a more fundamental level is, I'm sure, leading to my own habit of taking an allegory too far. Would the book benefit from a deeper analysis of physics? I don't think so. To take things much deeper would lose those of us without a deep rooting in mathematics. If anything, Greene's work should inspire us to learn more, to grasp the concepts at a deeper level, to understand them in a more fundamental way, if this is indeed possible with the strange world of quantum mechanics.

Greene does delve into what the future of physics could hold. This is, in my opinion, the weakest part of the book. While it is interesting to be exposed to what the 'next big thing' could be, without the grounding that Greene enjoyed in the previous four sections of the book the final chapters prove less fulfilling than the ones that worked towards them. It's not that Greene doesn't explain the concepts expertly, but knowing that we're reading about a theory that hasn't even been fully formed, that is only a step away from speculation, means they don't stand as tall as the previous chapters. People may say this about string theory as well, because it is still very much an evolving theory.

Still, this accounts for no more than the denouement of an otherwise thrilling, work. Having traveled once again with Greene on a journey through physics I can say that I understand what Feynman meant when he spoke of The Pleasure of Finding Things Out; thankfully Greene is a good bit easier to follow than Feynman.


You can purchase The Fabric of the Cosmos from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

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The Fabric of the Cosmos

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  • The Elegant Universe (Score:5, Informative)

    by Atticu5 ( 693001 ) on Tuesday March 23, 2004 @06:12PM (#8649716) Homepage Journal
    If you haven't seen the series of PBS specials, "The Elegant Universe", I recommend that you do. They're free for download from the PBS website IIRC. It's an excellent and very informative discussion of some very interesting concepts.
    • by Atticu5 ( 693001 ) on Tuesday March 23, 2004 @06:16PM (#8649765) Homepage Journal
      Heh, replying to my own post!

      As I mentioned, you can download "The Elegant Universe" from the PBS website here [pbs.org].

      It's divided up into 24 chapters -- 8 chapters for each hour of the three-hour series.
    • by Chmarr ( 18662 ) on Tuesday March 23, 2004 @06:32PM (#8649933)
      Unfortunately, in my humble opinion, the entire three, one-hour episodes could have been condensed down to about 10 minutes. There's a LOT of replay after replay of the same concepts, and even the same animation.

      Several times I found myself saying "okay, I get the point already, move ON." But, no, they hadn't gotten around to re-playing a bunch of (probably important and brilliant) physicists saying the same thing as every other physicist.

      It plays VERY much like the typical Sunday sports show... lots of "what you just missed" and "coming up next".

      If this is 'science for the masses', then the masses are very, very stupid.
      • "If this is 'science for the masses', then the masses are very, very stupid." You've got it in one. It never ceases to amaze me how stupid people can be... That's why democracy will never work.
      • by Audacious ( 611811 ) on Tuesday March 23, 2004 @08:13PM (#8650958) Homepage
        It isn't so much that the masses are so stupid as those who direct the product think we are stupid and film for the lowest common denominator. Thus, we drag everyone down to the lowest level rather than lift everyone up to the highest.
      • If this is 'science for the masses', then the masses are very, very stupid.

        You haven't spent much time with the masses, have you? :-/
      • by Mr. Piddle ( 567882 ) on Tuesday March 23, 2004 @08:55PM (#8651288)

        Several times I found myself saying "okay, I get the point already, move ON."

        This is a very self-centered statement. When I saw that show on PBS, my first thought was "This is great for a high-school physics class."

        People who understand education know that some repitition is important. Watch Blues Clues or Teletubbies for good evidence of this. Even adult education shows have summary segments after each topic.

        • Doesn't it depend on the scope of the repetition?

          I can perfectly understand a short summary after (and maybe before) each main section. (In fact, I remember that being given as advice for public speaking: "First, tell them what you're about to tell them. Then, tell them. And finally, tell them what you just told them.")

          But to spend just as much time again going over stuff without adding to it would seem a real waste. Is that the sort of repetition in the programme?

      • If this is 'science for the masses', then the masses are very, very stupid.

        You didn't know? You should do some tech support for a while, that'll learn you ;^)
      • My friends and I had the same problems.

        I think the issue is it was made into several episodes, and so they spend the first half hour going over things you learned in the previous episode, which made for a lot of repeating and telling things over, because they had to make sure you could start watching in the middle, which is where telling things repeatidly came in handy, so you don't get lost if you start in the middle, or a week passes between viewings, which is good to catch up, but makes for lots of stuf
  • by MooseByte ( 751829 ) on Tuesday March 23, 2004 @06:19PM (#8649793)

    It's kind of an ugly plaid corduroy, with elbow patches.
  • by ackthpt ( 218170 ) * on Tuesday March 23, 2004 @06:19PM (#8649799) Homepage Journal
    Sounds like an interesting read...if I want to continue lying in bed at night staring at the ceiling, with my mind completely blown.

    Recently I joined the local astronomy club [santa-cruz.ca.us] in Santa Cruz, CA. The night I joined the feature was a lecture, "The Mystery of the Ultimate Fate of Small Black Holes" presented by Donald Coyne [ucsc.edu]. The scope of matter, energy and time necessary for various things to take place is baffling, at least to me. Black Holes take a lot of time to be created. The Universe is estimated to be 13 billion years old. The theories put forth were such that black holes have formed and are dissipating (something about reaching a critical mass then collapsing in upon themselves, and kicking out staggering amounts of energy in radiation.) It seemed to me that for some of these things to have taken place the Universe would have to be older (as some of the processes would take longer than the universe has been in existence for.)

    It's fascinating stuff, but a little goes a long way.

    Oo! My widdo bwain, it bwoo my widdo bwain! Oo! Oo!

    • Yes a full sized blackhole would take a very long time to radiate away, but you could have had smaller black holes formed in the early universe.

      Would they fall into the gravity of the Earth and eat away at the Earth's core, dooming mankind forever? Will they?
      • Yes a full sized blackhole would take a very long time to radiate away, but you could have had smaller black holes formed in the early universe.

        As near as I can recall, from what Donald Coyne was explaining, black holes have a life span (albeit a very long one) which go something like this:

        A large mass forms, could be from a sun or suns.
        It continues to attact matter until it reaches a certain critical size (like 1500 lyr diameter!)
        Due to the extreme amount of matter accumulated it begins to collapse,

  • by ewall ( 557581 ) on Tuesday March 23, 2004 @06:21PM (#8649819) Homepage

    According to this daring young thinker [peterlynds.net.nz], our whole silly idea of time being a continuum from past thru present onto the future may be bunk. With the abolition of the time interval and precise measurements of place at a certain time, it solves some of the great mathematical paradoxes. You can read a better layman's summary and explanation here [eurekalert.org].

    The concept of time is so passe...

    • Reading through his paper, I am struck by the following flash of enlightenment:

      The concept of the limit is explained with more rigor in high-school calculus.

      Grade: D- See me after class
    • The concept of time is so passe...

      If you're going to cop a know-it-all attitude about it, I'm going to have to point out that you're about a hundred years off on this so-called "discovery":

      This Lynds fellow was born in 1975. But a metaphysician named J.M.E. McTaggert was writing on this subject from the early 1900s onwards. McTaggert is considered to be the modern originator of the whole debate, and anything Lynds contributed probably owes a great deal to him.

      Obligatory joke about how "nobody beat any

      • Glad to see someone talking about McTaggart at Slashdot. Those interested in modern philosophical theories of time (particularly Prior's) which take into account the efforts of modern physics to define the physical concept of time (often referred to erroneously as "the" concept of time), could start here [stanford.edu].

        Those really interested in the possibility of non-physical concepts of time should read Husserl (The Phenomenology of Internal Time Consciousness) and, most importantly, Heidegger (Being and Time).

        But onl
    • Rebels in Science (Score:2, Interesting)

      by MooseByte ( 751829 )

      "According to this daring young thinker, our whole silly idea of time being a continuum from past thru present onto the future may be bunk."

      Great theory! And it also goes to show why sometimes a relative outsider or unknown can be best at uncovering truly novel solutions.

      Those too well-versed in a certain field have often, by definition, already "drank the Kool-Aid" and bought into the belief system prevalent in said field at the time. As such their views and investigations are already prejudiced and

      • Rebellion is fine, if you're good at it, but sometimes the proper response for the teacher is to whack you with a stick and tell you to sit down and read enough of the last 400 years of mathematics and Natural Philosophy to figure out that, no, the common wisdom works fine, and that just because Xeno didn't have an adequate combination of mathematical knowledge or individual brilliance to overcome his paradoxes, that doesn't mean there's anything deep there. As a couple of other people have said, high-scho
    • With the abolition of the time interval...


      Once they'be abolished the time interval I can finally get my business plan to work:

      1. Profit!
      2. Abolish the time interval.
      3 ???
    • by meta-monkey ( 321000 ) on Tuesday March 23, 2004 @08:05PM (#8650876) Journal
      Wow.

      I just read this paper. As a physics major in college, I say, "Bullshit!" I mean, what an absolute load of crap. So, his great insight is "there's no such thing as any distinct point in space or time because if there were, then everything would be frozen." I understand he has no mathematics to back this up, and that's not why I'm condemning it. I'm condemning his work simply because his reasoning is completely circular. He claims there cannot be both discrete events and continuity because if there were discrete events then there cannot be continuity. Ummm...how about some evidence? How about something, anything to back up this idea? No, nothing. This is horrible garbage, and should be shat upon.
    • The museum of hoaxes [museumofhoaxes.com] has some doubts about Peter Lynds claims...
    • According to this daring young thinker, our whole silly idea of time being a continuum from past thru present onto the future may be bunk.

      Maybe I am misunderstanding you, but even according to respected physicists like Dr. Greene the idea of time as an arrow pointing in one direction is false.

      I saw him lecture a few weeks ago and he was excellent, so I ordered both of his books. I haven't had a chance to read them yet, but I am hoping one of them covers a concept from the lecture that really stuck out in
  • I like The Illustrated Brief History of Time more than the none illustrated version. I saw Elegant Universe on PBS and really liked the visuals. Mr. Greene - give us non-geniuses more visuals to help understand this stuff.
  • Time for time (Score:5, Interesting)

    by 31415926535897 ( 702314 ) on Tuesday March 23, 2004 @06:22PM (#8649838) Journal
    I have found the concept of special relativity particularly fascinating. The way that Einstein described spacetime I still find to be quite neat, even though it's a (relatively) old theory at this point. It seems like we're on a speed-of-light course through this universe, and when you're relative velocity is 0, then you are traveling through time at the speed of light (if such a concept can be grasped), and conversely, when you travel at the speed of light, then time is stopped for you (so that the vector sums of velocity through space and time always add up to the speed of light). The simplistic genious of that blows me away, and I love reading any material that has any more insight or explanation into relativity. I even find quantum mechanics to be interesting to study (though the math sucks).

    I bought The Elegant Universe a few years ago, and I loved it. I think this is definitely going to be worth checking out at the library.
    • when you travel at the speed of light, then time is stopped for you That solves the conundrum of "If you are driving at the speed of light, and you turn on your headlights, what happens?" You can't turn on your headlights, since time has stopped for you! However, doesn't this make it a little difficult to navigate when your traveling at the speed of light? Or more to the point, doesn't your relative reaction time get slower the faster you go?
      • "However, doesn't this make it a little difficult to navigate when your traveling at the speed of light?"

        That's why light goes though a "straight" line (but can't be bent from the outside. Yeah, I know, I make no sense, but this IS slashdot.
    • Re:Time for time (Score:4, Interesting)

      by forgotmypassword ( 602349 ) on Tuesday March 23, 2004 @07:56PM (#8650784)
      Even better was that Einstein described space and time in an axiomatic manner. Einstein defined time as what is measured with a clock and distance as what is measured with a ruler.

      Philosophers had long since refuted earlier definitions involving inherent coordinate systems and what not. The axiomatic definition is the only thing that has held up to scrutiny. But of course its axiomatic so it doesn't have much in the way of understanding.
  • What is time? (Score:3, Insightful)

    by EFGearman ( 245715 ) <EFGearmanNO@SPAMsc.rr.com> on Tuesday March 23, 2004 @06:24PM (#8649858)
    Time is what prevents everything from happening at once.
  • by CarlDenny ( 415322 ) on Tuesday March 23, 2004 @06:26PM (#8649874)
    I finished Elegant Universe a few weeks ago, after having put it down for most of a year because I couldn't stand to read another rehashing of QM, relativitiy, isn't this weird. After skipping those chapters, the second half was quite engrossing.

    Is it worth reading this if you already read and enjoyed Elegant Universe, or is it just a watered down version without explaining the math?

    I would hope a reviewer would give a little more insight into whether to read it or not.
    • Hrm... Possibly. This is, in many ways a lighter read when it comes to M/String theory, not delving so deeply into Kalabi-Yau transformations and the other of Green's work. If you're looking for more in-depth on Strings this might not be the work for you.

      It's a better overview than TEU was, Green's prose is more refined, but the level of the target audience is lower as well.
    • It is watered down. Its emphasis is a little different than TEU, with less discussion of string/M Theory and more discussion of quantum weirdness, relativity, entropy, and the arrow of time. If you enjoy reading about physics (and apparently you do), then most of this material is probably review for you.

      One thing that I found interesting was the discussion of how inflationary expansion affected the structure of the universe, and in particular how it put the early universe into a very low-entropy state.

      I
  • by Akilesh Rajan ( 121685 ) on Tuesday March 23, 2004 @06:28PM (#8649893)
    Disclaimer: I'm not a physicist, and don't even know that much about physics, but I'm very interested in the philosophical implications of Greene's view of time, or what little I read of it.

    I briefly read one of this book's chapters on time, and it doesn't seem to explain much. Greene argues that time doesn't flow by pointing out how, due to special relativity, events in my future may be in someone else's past.

    Therefore, Greene concludes, all events, past, present, and future, must already exist and must always exist. And our sense that time flows is an illusion.

    Interestingly, Greene explicitly REJECTS the notion of a "projector" illuminating one cross-section of this frozen river of time one piece at a time. He rightly sees the problem with this analogy: when does the projector operate? It would have to operate at no time at all, so the concept is incoherent.

    How does Greene account for flow? He says that the feelings, thoughts, and perceptions one has at any particular point in time contain sufficient context that one senses their relationship to the past and to the future. This we call flow.

    My problem with this explanation is that I don't think you can have thought without change. I don't think there is reason to believe that there is a fundamental unit of time, within which some kind of fundamental unit of thought would exist.

    Thought is inherently based on movement or change in our mental landscape, and this movement must happen in time. There is no possibility for thinking without flow. Thinking cannot account for flow, but rather assumes it.

    Also, if we take the frozen river hypothesis, how do we find ourselves at one point in time and then at another point in time... how does this movement ever occur? And to whom? Wouldn't we be locked helplessly at our one "point" in time?

    Finally, even if special relativity does show that events in one person's future may subjectively be perceived in another person's past, the very fact that we can correlate these two pieces of information: does that not show that there is some master set of times that relates everything to everything else?
    • Just kind of wondering, do you consider thought to be fundamental to the point of working on all scales?

      The way I would resolve that kind of issue would be to think of thought as basically a chemical process which doesn't arise until time scales so large that the difference between time being a flip-book and time being continuos are irrelevent. (I.e. for thoughts that take significant fractions of a second, time being cut into sub-femto-second slices or being truly continuos doesn't make much of a differen
  • Why is there time? (Score:5, Interesting)

    by LinuxParanoid ( 64467 ) * on Tuesday March 23, 2004 @06:30PM (#8649916) Homepage Journal

    On this subject, I always liked Max Tegmark's [upenn.edu] speculations on the topic, which includes some assessment of why we have only one, and not zero or two or more temporal dimensions.

    There's lots of other cool stuff on Max Tegmark's site [upenn.edu] too if you want to procrastinate on whatever else you're doing. (He's a physics (astrophysics?) professor at U.Penn.)

    --LP
  • by Lakedemon ( 761375 ) on Tuesday March 23, 2004 @06:31PM (#8649920)
    Time is what you lost when you started reading /.'s stories.
    Space is what you lost when you started downloading things.
    Just common knowledge...no need fo a book to grasp that.

    Wait ! I got it !

    Money is what you lost when you bought the book when you could have just read my post.
    =P
  • to tackle the very question of 'why is time?' and 'what is space'?

    ... not to mention other important questions, such as "When is the universe?", "Who is matter?", and "Where the hell is the remote?"

  • Time is what keeps everything from happening all at once.

    Simple as that.
  • NPR interview (Score:5, Informative)

    by paulerdos ( 205999 ) on Tuesday March 23, 2004 @06:37PM (#8649978)
    there was an interesting NPR interview with greene about his new book last week:

    http://freshair.npr.org/day_fa.jhtml?display=day &t odayDate=03/16/2004
  • to tackle the very question of 'why is time?'

    I never thought time was a terribly complicated topic. It boils down to change. If nothing, and I mean nothing at all, ever changed, then time hasn't passed.

    How can you say it has? If nothing has changed, you have no way of judging, measuring, or scaling 'time'. Time is the difference between one moment and another.

    Think about dimensions. I've often heard the '4th' dimension referred to as time. Well take an object in the 3rd dimension and 'graph' its c
  • Cause I don't have time to read it.
  • Considering my office is right down the hall from his, and I finished his book a couple weeks ago, I'll throw in my recommendation for JR Gott's "Time Travel in Einstein's Universe".

    Very interesting read which explains things in a manner that I could understand (sysadmin, not astrophysicist, though I'm surrounded by them daily). Maybe I should send in a Slashdot book review too :>
  • by rixstep ( 611236 ) on Tuesday March 23, 2004 @07:35PM (#8650612) Homepage
    This is all very intriguing but I have a lot to do. I'll look at it yesterday when I have more time.
  • ...is "The Gifts of the Jews," by Thomas Cahill. In it, he postulates that the Jewish people were the first to introduce the concept of linear time into a world of circular time. It's a very humanitarian treatment of time, as opposed to something Hawking might put out. It's definitely an interesting read, regardless of how twitchy your Godometer is.
  • Time is an illusion. Lunchtime doubly so.
  • Just after the PBS special was made available online, I put together a page with links to all the segments here [ucla.edu]. That way my friends who were interested could download them and watch them later.

    - sm
  • I just saw that NOVA is running "The Elegant Universe" this evening.
  • " Everyone understands the concept of time to some degree, yet to explain why time is, is a mental puzzle that has played in the outskirts of my mind for years now"

    if you can't explant it, you don't understand it.
  • This is actually a few responses rolled into one...

    The first is, that I love it when somebody who has a full grasp of a profoundly exciting and difficult to understand field, like advanced physics, breaks down the critical concepts and presents them for general consumption. It's important to understand the way our universe is put together. It gives you a better idea of your place in the universe, how one actually relates to all things... the great and the infinitesimal. It also demands that you build up
  • Time is. . . (Score:3, Interesting)

    by Fantastic Lad ( 198284 ) on Tuesday March 23, 2004 @10:29PM (#8652010)
    a function of brain damage.

    We are all really, really broken in the head. Time, as we experience it, is a total illusion. --But it is an illusion which allows for the perception of physicality; --if you were aware of all possibilities existing at the same time, you would perceive of yourself as being something rather like an ever-evolving smear.

    Every choice you make in your current brain-damaged, "single-frame advance" form is what takes you from one step to the next. In the fully aware version, physicality becomes variable, because you can focus on a reality and pull it into being by exercising choices across an entire 'life-time'. Existing in that form, I suspect, probably comes with it's own version of 'time', because that level is probably just a brain-damaged version of the next one above it.

    Don't bend your mind trying to picture this stuff. You are mentally impaired and you can't do it. Things are changing though. All those little introns are wiggling around and beginning to come active in those who are struggling to wake up! Lots of perceptive abilities which haven't been expressed yet. . .

    Some of you will have already started experiencing brief bleed-throughs as the paradigm shift rushes ever-nearer. --Here are a three of the multiple reality 'encounters' I know of, (the last two of which I've directly experienced).

    -Being able to see both behind you and in front of you at the same time.

    -Being able to see both the front and back of stationary objects in an 'impossible' way.

    -Seeing several versions of one person super-imposed in the same area.

    Stuff like that. Yes, quite terrifying, but they only last a few hair-raising moments, and you can snap out of them at will, (for the time being anyway.) Watch for them and learn from them; you'll need to be able to stay calm if you make the transit. And yes, all of this while not on drugs. Drugs are for idiots; they'll just weaken your ability to deal when the shit hits! Gettin' closer real fast, kids!

    When? Well, the shit is supposed to hit at the same time as the big cloud of comets wipes out everything on this planet. Be a nice time to be able to morph your reality, eh? Otherwise, it's apocalyptic fire storms for you! (But don't sweat it. You'll just reincarnate where you need to. It'd be cool to actually make the transition without dying, though! And certainly into a reality where there isn't an ice age in full swing and nothing left but smoking rubble and black glass.)

    Final note: I don't care what you believe, no collection plate will be passed, there is no book to buy and no representative will come to your door. Deal with it. (And no, I have no relation to 'Time Cube' guy. He's just insane. Whereas I'm the guy who is going to haunt your thoughts every time you trip over something which jars your reality. --Unless, of course, you're already way ahead of me, in which case, 'Cheers!')


    -FL

    • > Time, as we experience it, is
      > a total illusion.

      C.S. Lewis talks about this - he asks (paraphrasing): Why are we always surprised by the passage of time? Why do we say 'oh my goodness, little Billy has grown so fast'? It's as if a part of us is eternal, and is unable to completely come to grips with a life that's contained by a linear, finite span of time.

      Another Lewis quote, this time verbatim - "The difference [God's] timelessness makes is that this now (which slips away from you even as you s
    • Re:Time is. . . (Score:3, Informative)

      by gribbly ( 39555 )

      You speak of brain damage with convincing authority.

      Believing that you are one of "the last generation" is surely one of the most common fallacies of the credulous.

      Also, you mean "Timewave", not "Time Cube".

      In any case, you should probably read this article [pthbb.org] on the Copernican principle of events. The overwhelming likelihood is that you're not special, friend. Sorry.

      Oh, and of course "drugs are for idiots". Like Carl Sagan, you mean? Got it.

      grib

  • by S3D ( 745318 ) on Wednesday March 24, 2004 @03:24AM (#8653714)
    Related site about physics
    Jhon Baez site [ucr.edu]
    especially interesting
    Open Questions in Physics [ucr.edu]
    Alternative approach - quantum gravity without strings Building Spacetime from Spin [ucr.edu] - this theory have some troubles - they arn't able to get a flat space-time as a classical limit of their theory, but now they are tryng apply the same approch to strings - a lot of math which I don't understand, but little part which I understand fascinating...
    • by ynotds ( 318243 ) on Wednesday March 24, 2004 @05:20AM (#8654094) Homepage Journal
      The most eloquent of the group promoting loop quantum gravity as an alternative to string theory, Lee Smolin, makes what I believe to be a significant point that string theories, like quantum theory but unlike general relativity, are background dependent, that is they just assume the existence of spacetime rather than establish it.

      Yet there is something about all current approaches that smacks of epicycles. Great scientific theories have an elegance which appears to be missing from current attempts to bridge the gap between the micro and macro domains. Theory needs that kind of elegance and the wider comprehensibility which comes with it to be accessible to real critique.

      If those who have not shared a lifetime of indoctrination are unable to play in the sand pit, the "experts" can get away with ever more circular cases of theoretical blinkers and instrumental blindness which only ever return the answers they are looking for, as well as all the funding advantages that come from having sidelined the nay sayers.

      One side of me wants to suggest that our current infatuation with anything to do with information really might produce A New Kind of Science which breaks down a few barriers, but the only honest position is that the jury is still out on that one too.

      Some of my own work hints that computer models of seemingly irreversible systems readily generate local time reversibility and that starting inflation may be a lot easier than stopping it, but leaves some other fundamental phenomena needing to be explained within the same frrame of reference. I mainly try such experiments to get a better feel for the state of play and right now my best estimate is that the next real revolution in physics might still be a generation away, but that one is coming.

  • by jandersen ( 462034 ) on Wednesday March 24, 2004 @04:38AM (#8653957)
    Sigh. I really wish there would be fewer, but weightier attempts at making science understandable to people. The trend in recent years to try to make everything in the form of infotainment simply hurts everybody's understanding of things - people end up having a kind of view of science that only fits into a Superman cartoon - you know, where 'mutations' can magically change a person into a slimy monster, temporarily, and where 'X ray vision' can look through 10 miles of granite, but not 1 millimeter of lead, etc etc. Even Startrek did a better job of popularising science than much of what I have seen recently.

    As for the fundamental understanding of time and space - there is literally nobody, I'd claim, who understands this, which is why we see such concepts launched as eg. 'quantisation of space and time', which is profoundly nonsensical. (the reason, if you must know, is that since we live 'inside' space, we have some considerable difficulty seeing space from 'outside', which is where this discontinuity would be apparent).

    The truth is - physics is stuck in a rut, and we need a fundamental change in viewpoint before we can progress any further. String theory and quantum mechanics are all very well, but they all build on ideas that are now about a century old, and which have been stretched to their limits. The Copenhagen interpretation hasn't really helped either - this massive block of philosophy stating that 'there is nothing smaller than whichever quantum limit' has been a religion that has done a lot to block our progress towards a better understanding of things on a small scale. In case you'd care to know - all quantum mechanics really says (in this respect) is that because of the dual wave-particle nature of matter, it is impossible to measure things on an arbitrarily small scale using only particle interactions; this clearly doesn't mean that there is nothing going on there.

    To compare: imagine that we try to observe ships in the ocean by standing on the beach and making waves - we wouldn't be able to 'see' ships smaller than the length of the waves. So to se better, we create shorter waves, but since they contain more energy, they push the smallest ships around, so we can't locate them precisely. Does this means that there's nothing smaller than what we can observe? Of course not - we just need to find another way to observe them. The limitations in quantum mechanics are more about limitations in the observation methods than about reality.

"Our vision is to speed up time, eventually eliminating it." -- Alex Schure

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