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Science

Black Holes Don't Exist??? 163

Posted by Roblimo from the pop-science-can-be-fun dept.
OldSoldier writes: "Here is an article that was first published in the April issue of a small SciFi magazine called Analog. The author, John Cramer, is one of two columnists for the Alternate View column and his columns are very thoughtful and more grounded in science than most. In particular, this article states that there is a small but growing group of physicists who have come up with an alternate formulation to Einstein's General Relativity equations that do two rather stunning things. One is that they allow super massive non-black hole objects and the other is that they are able to be quantized. If you like this article, I suggest you go to his index and read some of his previous articles."
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Black Holes Don't Exist??? More

Black Holes Don't Exist???

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  • Re:Slashdotted... (Score:3)

    by 0xdeadbeef ( 28836 ) on Sunday May 14, 2000 @06:49AM (#1074124) Homepage Journal
    Hasn't the recent Microsoft debacle taught people anything? You can't post a copyrighted work in it's entirity without permission, even if it is slashdoted. That goes way beyond the provisions for fair use, and only encourages people to start reducing the simplicity of accessing information.

    Do you want slashdot to become like those theiving commies at FreeRepublic?
  • Could you learn how to fucking spell, you ignorant bible thumper?

    1. I am not an ignorant bible thumper (I don't even know what that means :). The fact that someone is a Christian doesn't mean that he can't have solid arguments agains theorems like the evolution theorem.
    2. English is not my native language (I'me Dutch) and I could have written an entire essay in Dutch, but unfortunately > 99% of the slashdot audience doesn't speak Dutch. I've tried to filter out most of the spelling errors (it took me ages to write the piece :).
      If you can write 50 lines of correct Dutch for me then you have point :-)

  • That "resistance" to new ideas has two causes, one good, one bad. The bad cause is that scientists, as human beings, sometimes put their ego in their ideas and get offended when their work is challenged. The good cause is that 99% of challenges to "big theories" are idiotic cruft akin to claims of perpetual motion machines and trisection of angles with a compass.

  • Granted, but even if a model has many successes, it doesn't necessarily mean that it is correct, but instead only an approximation with no better theory. For example with newtonian theory, it produced alot of good results, but was totally overthrown by general relativity. It only follows that advances in science will show that general relativity itself is only an approximation as well. Even string theory may turn out to be only an approximation (even though we are nowhere near proving or disproving it).
  • First, if anyone has pointers to heavier articles, please put 'em up. I found a couple of discussions, but I lost 'em...

    It seems that what Prof. Yilmaz is suggesting is that the potential energy of gravitation be included in the energy side of the equation (yes, adding an extra term). To my non-mathematical visual (i.e. probably wrong) conception this implies that a very strong gravitational field bends space more under GR-Yilmaz than standard GR, meaning there might be more space at the bottom of the well, and matter might not have to compress so small to appear to occupy such a small space. According to those who have done the math, it already predicts 10xSolar mass neutron stars, so a "black hole" would have more mass to get started with...

  • Re:Recent steps toward Super Unification (Score:1)

    by Anonymous Coward
    It should be noted that many people consider M-Theory (and string theory for that matter) to be total garbage. Any good physicist knows the fuzzy foundations of quantum mechanics and even quantum field theory (despite QED, the electromagnetic field theory, being the "most numerically accurate" field of physics, it has hardly been tested outside of the highly controlled accelearators). General relativity suffers from the same problems as any new field. It has axioms which may or may not be true, and sometimes you don't even know what all the rules are (such as the Gibbs paradox in some statistical mechanics problems, where even in the nonquantum theory you need to treat particles as indistinguishable; this is generally considered a very "quantum" thing to do).

    I hope I have not gotten too far off subject, but I would not treat the comments in this response as any more profound than a GR solution where black holes may not exist. Theoretical physics is a very hard game to play, and when there is no experimental data to go on (such as the time, distance, and energy scales string theory and M-theory propose to explain phenomena), it's easy to join the bandwagon and play with the math that most theoretical physics so love, especially when so many big shots have gotten into the fun.

  • Theoretically this would be possible, but the amount of energy to resist the pull of gravity as you cross the event horizon would be infinite. On a less theoretical angle, the tidal forces as you approach the event horizon of any black hole smaller than a galaxy-swallowing monstrosity would probably be fatal to you and your spaceship.

  • I suspect that you postulate 'organisms' and 'species' as real things that evolutionary theories predict the behaviour of. Some theorists haven't - they have regarded the immediate sensory perceptions of our mind as reality, and 'organisms', 'society', 'sub-atomic particles', 'people' etc as tools to predict immediate sensory phenomena (and then there's the problem of defining what a single, irreducible sensory phenomenon is for the purpose of predicting them).

    Actually, if pressed to explain my view of reality, it's a lot closer to these theorists you describe. I view my perception of physical reality as the best model of the sensory inputs I receive that I can find. I very well could be a "brain in a vat," but the point is irrelevant because I can't distinguish that hypothesis from the hypothesis that the universe is "real." Thus I might as well apply Occam's razor and use the simpler hypothesis, that being that the inputs I receive are the result of direct physical reality.

    A similar argument disposes of the tenets of many religions as unnecessarily complex models of the universe which tell no more than do nontheistic scientific models. Occam's razor allows me to say that as long as I see no direct evidence for a transcendental force in the universe, I need not consider religion.

    Anyway, whatever. You've prolly heard these arguments a thousand times over from more intelligent people :).

    Your post was a lot of fun to read, thanks.

  • (WOTB) way off topic, but...
    Actually most search engines cache web pages. That's how they are able to show context when you serach for something. They just don't make it available to the users in it's entirety. In my opinion google does violate copyright law. The thing is they remove the cache for anyone who complains so so far they have avoid lawsuits. I think it will take a court case to decide the issue. The other search engines don't appear comfortable being the first to have such a court case.

    The caching is only really needed for sites that are frequently down or unavailable. These sites probably don't have the money to sue. Also, since google only updates pages every month or two it's not likely to take away from ad hits of big sites.
  • You don't need a singularity to have a black hole.
    No event horizon? "Oops, Jim, didn't mean to come this way, let's turn around and go back"
  • The Hawking radiation effect seems to assume
    that more "negative energy" halves get absorbed
    than positive. Statistically I would assume it
    would be 50% either way, so there would be no
    net radiation.

    Thus this test may be invalid for reasons
    other than testing for a singularity.
  • Comment removed based on user account deletion
  • Hmmm, and people like you who take out of context see what?

    Certainly not the full equasion "T1 = T2 k"

    Ah, following Mr. Albert E. Uh err, Alfred E. Newman..
    3 S.E.A.S - Virtual Interaction Configuration (VIC) - VISION OF VISIONS!

  • In a finite amount of whose time? The proper time taken for the surface of the star to collapse is most assuredly finite. It takes an infinite amount of coordinate time (or proper time for an observer 'at infinity'), but so what? None of those people are in a position to observe that the surface hasn't actually gone into the hole.


    The salient points are:

    1. For anyone sitting at a safe distance, the hole looks like a hole and acts like a hole. For all practical purposes it is a black hole.
    2. There is an event horizon and a region of spacetime on the other side of it which cannot communicate with the outside spacetime.
    3. The surface of the star does eventually pass into the region of spacetime beyond the event horizon in a finite amount of its proper time.

    In other words, real holes have all of the important features of theoretical holes; they differ only in minor details.


    -rpl

  • Anyway, whatever. You've prolly heard these arguments a thousand times over from more intelligent people :).

    Well maybe. They're perfectly reasonable arguments and they've been used by a lot of intelligent people :) But that's OK. Everyone has to apply Occam's razor at some point. You seem apply it more at the practical level, so that you can express what you experience in 'everyday' ways, and some people apply it at the theorectical level (ie simplest explanation == most 'right' somehow).

    There's nothing wrong with holding views that other people have expressed before. I hold that there really is an external world which bears some relationship (somehow) to the way in which we expereince it, but I bet a lot of more intelligent people have said that before too :)

    Your post was a lot of fun to read, thanks.

    That's OK. :)

  • God by definition (or at least by most definitions of God given by Christians) is infinite, all powerful, all knowing, and all encompasing. By definition God is also "supernatural", or rather, beyond nature.

    By definition, therefore, God cannot be measured, quantified, or otherwise observed scientifically. As God is God, He can change the rules, alter reality, change the very structure of the universe at his will. Or, if you are a deist, at the very least he set the wheels of the universe rolling before the Big Bang, and set a perfect universe in motion.

    Either way, you cannot describe the nature of God scientifically. Therefore, science has nothing to say about God (at least, good scientists will say this), and so being both a theist and a scientist is not inherently incompatable. Actually, science and theology are orthogonal--so one can be both a scientist and a theist (or not) without consequence.

    Well, without most consequence, as one's morality may alter one's behavior. So your morality towards little mice may affect your willingness to kill and dissect the little fuzzy things in the name of scientific research.

    Oh, and I'm native american.

    Beyond that, I've spent quite a bit of time asking people what they believe. And what people have said is that "God is infinite." One consequence of the infinity of God is that God is unknowable--as it is impossible for the finite to encompass the infinite.
  • Except that the theory proposed claims that there are no infinities... as in no infinite gravitational fields... no event horizons.

  • Recent steps toward Super Unification (Score:3)

    by Anonymous Coward on Sunday May 14, 2000 @07:05AM (#1074141)

    I have been following physics for quite some time and have seen the difficulty in trying to formulate a Quantum Theory of gravity. I think that we will find--very soon--the bridge that crosses the gap between General Relativity and Quantum Mechanics.

    One of the more promising theories, as of late, is called M-Theory [ucsb.edu]. It is able to unify all five "types" of super strings. This view of sub-nuclear physics also attempts to answer a lot of questions about cosmology. This would include the actual number of dimensions in space-time and the actual structure of universe, itself.

    The problem with the original Super String Theory was that it lacked "testable" predictions. The energies required to probe to that level were in the range of around 10^16 TeV. However, there has been some recent speculation that some of the extra dimensions could be larger than the Planck length (10^-34 m). Physicists were hoping to catch a glimpse at these higher dimensions by observing the effects of gravity at close range. [hep.net]

    Some believe that gravity may propagate through more than three spacial dimensions, since it is so hard to unify with all the other fundemental forces. If this is the case, then gravity will fall off at a rate greater than the square of the distance. This would also mean that super-unification would probably happen at a lower energy scale (in the TeV range), as opposed to the dreaded 10^16 TeV range.

  • Einstein is known to have not believed in the physical reality of the mathematical singularaties generated by his own equations. He wrote, "For large densities of field and of matter, the field equations and even the field variables which enter into them will have no real significance. One may not therefore assume the validity of the equations for very high density of field and of matter, and one may not conclude that the 'beginning of the expansion' [of the universe] must mean a singularity in the mathematical sense. All we have to realize is that the equations may not be continued over such regions."
  • Briefly:

    - if you like grade-A SF, read Analog it is the best SF magazine out there and has been for decades IMHO.

    - If you like concise, factual, exploratory science, read Analog. Their science fact articles are the best in the business.

    - if you want to read some facinating summaries of what is happening in physics, read John Cramer's Alternate View columns in Analog or on his web site.

    - if you want to read some rousing good Hard SF novels, read John Cramer's TWISTER and EINSTEIN'S BRIDGE. Good stories, good characters, good science.

    'nuff said.

    IV

  • Holländische Leute sind dumm.
    That's German (meaning "Dutch people are dumb") and no, I'm not dumb.
  • The exception to this rule is the gravitational field itself. While there is energy stored in the gravitational field, unlike all of the other known energy fields (the strong, weak, and electromagnetic interactions) the energy present in gravitation does not, in conventional GR theory, produce space curvature. Starting with Einstein, the justification for this is that to have gravitationally-produced curvature would be "double counting", that since gravitation was produced by the curvature, it should not make more curvature
    I thought that gravitational energy did create more curvature. This is one of the reasons that GR results are hard to obtain, as the theory is fundamentally non-linear. That's what at least one of my physics texts says.
  • Einstein is known to have not believed in the physical reality of the mathematical singularaties generated by his own equations.

    He wrote, "For large densities of field and of matter, the field equations and even the field variables which enter into them will have no real significance. One may not therefore assume the validity of the equations for very high density of field and of matter, and one may not conclude that the 'beginning of the expansion' [of the universe] must mean a singularity in the mathematical sense. All we have to realize is that the equations may not be continued over such regions."

  • > If this is right, it means that there are probably only 4 dimensions to spacetime,
    > not 26 or even 10.

    Damn! Then what feature are they going to add for Quake XMVLX??

  • Re:Scientist are not always right ... (Score:5)

    by Lupus Rufus ( 11262 ) on Sunday May 14, 2000 @07:26AM (#1074148) Homepage
    I identify to some extent with the exasperation inherent in your post, but I have a few criticisms of your content.

    First of all, with the word "theorem." My area of expertise is mathematics, and in math a theorem is any statement which can be shown to be a logical consequence of axioms assumed at the outset. Now, in math we use a bunch of set theory axioms as the foundation of theorems, and in fact (strange as it may seem) all theorems of mathematics can be formulated as statements in set theory and proven using these axioms.

    Physicists have also been known on occasion to use the word "theorem" (Noether's theorem from mechanics, Hawkings' theorem on existence of singularities in GR), but physicists also restrict themselves to the strict definition of theorem--theorems are always logical derivations from basic assumptions (which in physics take the form of hypotheses).

    Secondly, I will agree that scientists have an underlying assumption that the world works in a consistent, predictable manner. However, I personally consider this assumption to be an hypothesis, i.e. just as falsifiable as any other proper scientific theory. This hypothesis has a major prediction--roughly, that natural processes proceed the same everywhere and at all times. The existence of such wonderfully verified theories as evolution, quantum theory, and yes, GR, is testament to how remarkable this theory is.

    Anyway, my point is that GR is a theory, and placing it as an axiom one can produce theorems like those of Hawking. GR, however, is perfectly falsifiable, and so if this alternate theory turns out to predict phenomena better than GR, eventually it will inherit acceptance. This doesn't, however, mean that physicists working in GR right now will lay down immediately. Partisanship is an important part of the scientific process--without a healthy debate about theories, ideas get stale. The result is that scientists end up adopting the theory which has been least falsified. And I have every confidence that if GR is shown to be substantially more inconsistent with observation than this new theory, then Hawking and everyone else will accept it.

    BUT, this does not mean that you can just go around claiming that scientists who have no alternate theory for, say, evolution are necessarily not open-minded. In my opinion, comparing evolution and quantum theory to GR suggests a severe lack of understanding. Evolution has been around for 150 years and itself has been a continuously evolving theory, changing as more information is uncovered. Somehow, however, the basic idea (that species arise from differential change within other species) has stood the test of time. Quantum Theory is very similar--the Standard Model is one of the best predictive models in science, and has been ruthlessly tested in particle accelerators for half a century. GR, on the other hand, is one generalization of special relativity (which has been heavily verified on a microscopic level), and its interesting implications are all in a high-gravity context, about which we have very little direct information. As this new theory agrees with GR for low-gravity environs (like our own), it seems to be a reasonable alternate theory. Whenever you have an area of science where data is not in much abundance, multiple theories will crop up. But usually, large bodies of evidence (like that for quantum theory and evolution) will leave space for only one major theory.

    Sorry for the rant. I just get irate when people try to argue about science without the proper context.

  • You don't need a new formulation or interpretation of the General Theory of Relativity to come to this conclusion either. This has been known for many years. Still, people, including many scientists make the error that a star can collapse to a point of zero size, as seen from our timeframe. This is not possible. As a star collapses, it is subject to its own gravitational time-dilation. The collapse, as seen from outside, would appear to slow down the closer the star became to its own event horizon, with this boundary as the limiting condition. It would take infinitely long to actually reach it. In order to see the star collapse to zero, you would have to match its timeframe, by jumping into it! (and living! Also, an infinite amount of time would pass outside, so the universe would end and you would have no way of telling anyone your discoveries.) So, a more correct (and commonly used) term for a black hole is a "frozen star." This is also the title of an excellent book by astrophysicist George Greenstein which introduced this idea to a wide audience.

    It is still an open-ended question whether these processes would still be upheld in the creation of "primeval" black holes that really are of point size, or at least smaller than their event horizons, that were created by the Big Bang.
  • Yes Sir. Sorry Sir.
    I won't do it again. Free speech is evil.

    Seriously though. Do you really think the auther who wrote the artical really cares, if you tell people that you got the artical from him?
    It's not like he posted a secret, or clamed that he wrote the artical.

    It also wan't really redundant either. A few posts up, someone was complaning that the site was slashdoted. So they couldn't read it.

    You have something against communists? If so, And you can do it in a intelligent manner, I'd like you to tell me why.

  • 1 is a number so is 2, 3, 10, 1000000000, 36478263462684322x7432974827479222/432432423423423 +435733387979 to the power of 857495793.

    But infinity is not a number, or else you'd be able to count it. Just like 0 is not a number, something that doesn't exist can't be a number. Something that represents and ongoing array of numbers, can't be a number either.

    So before you go leaping off and deciding whether or not black holes exist. I think you need to get some basic maths right first.

  • Scientists believe that singularities are points of infinite density that are produced when a massive star collapses under gravity. What I don't understands about singularities is why they are presumed to be infinite with all the mass at the same place. Heisenburg's uncertainty principle states that the position and momentum of a particle or object cannot both be known to arbitrary precision. Surely this means that the singularity would be "smeared out" somehow? You would still have a singularity, but because it's smeared out, it's no longer infinitely dense, just very large.

    Can someone help me out here? Or is the answer to this going to have to wait until we have the unification of quantum mechanics and general relativity for which physicists have been seraching for sixty years, and I'm out of luck?

    --

  • Hypothesis (pl?) are based on hunches, science is based on results of experiments. Until you have the results to back up a theory it's up there with "aliens cause 1% of all miscarrages in the US". There are no results to back up singularity theory; I am not aware of the ones you mentioned for event horizons.

    In lieu of doing any work this morning here is a run down of my "hunch":

    1. Super-dense objects do exist.
    2. GR is an astoundingly good piece of work. Probably the single best in physics, althoug QED runs a close second.
    3. GR does not adequately handle the physics of super dense objects, as you have implied several times. These are so rare that it makes no difference for most applications of GR, just as the rarity of high speed objects made no odds to Newton's laws of motion for most applications.
    4. A singularity is so outlandish that I, given the choice of accepting something which is totally atypical with the rest of the physical universe and assuming that it's just a sign that some other, unknown, aspect of the problem needs to be taken into account, generally choose the latter.
    5. If there is something else to be taken into account (eg, quantum gravity) then the implication is that there is a point where that will produce a deviation from GR. Just as, for example, Mercury showed up the "flaw" in Newton's mechanics.
    6. That point must be in regions of space under conditions very far removed from those we occupy and normally study.
    7. The implications of this include the fact that we don't know where the divergence will be and that it might be before even the even horizon forms around a super-dense object. We just don't know.

    Well, that's how I feel about it. I know there is a lot of grant money (and book money) based on assuming there is nothing more to be learnt about these objects, but I personally think that's a very odd thing to assume.

    Why are you so sure that GR is wrong (because it's not a quantum theory) but that we can still extrapolate from it into regions of uniquely extreme characteristics?

    As for the belief that physics is more or less complete -- no one knows that. However, it's a fairly necessary working assumption in science. If you assume that everything you know is wrong just around the corner where you haven't done an experiment yet, then you're left with nothing.

    No, no, no, no.

    Is is a necessary working assumption in science that what you know MIGHT be wrong. That's why we keep testing old theories. You are suggesting a return to dark-age dogma.

    Science is the application of the old Sherlock Holmes quote "once you have elimiated anything which is impossible, whatever you are left with...is the answer" with the modification that we don't actually start with a full list of the possibilities. Science is more about finding out what is false than about finding out what is true - we almost never know that.

    Understanding that does not "leave you with nothing", it leaves you with an open mind which is ready to overturn superstition, false claims and ignorance.

    TWW

  • [I have not got my degree yet but...] I'd be surprised if it affected the possibility of FTL travel by simple acceleration (I mean, you still won't get FTL with a rocket or anything) as:
    1) That is a practical certainty from experiments with particle accelerators and the like - we simply can't accelerate a particle beyond the speed of light
    2) This new 'GR' agrees with conventional GR in the low-field limit, and so probably agrees with Special Relativity which forbids conventional FTL
    3) This is an example of an infinity which is never physically realised, whereas the black hole - style infinities are, in conventional GR, physically realised. By that I mean you can't ever reach the 'lightspeed infinity' but you can reach the 'singularity infinity' IF GR is correct.
    Having said that, the few tentative possible FTL methods like wormholes and Alcubierre drives are very much a General Relativistic effect involving gravity and so could possibly be affected if this new theory is correct.

  • Damn ... (Score:3)

    by Troed ( 102527 ) on Sunday May 14, 2000 @04:45AM (#1074155) Homepage Journal
    ... think of all the SciFi material we have to rewrite now!!!
  • I would just like to mention that Yilmaz theory of gravity has been already discussed at length in sci.* USENET newsgroups several years ago. You can find these discussions archived here [washington.edu] where you will find what are experts objections.
  • Science is based on both hypotheses and experiments. Do you understand anything of the development of scientific theories? Sometimes experiment leads theory, sometimes theory leads experiment. Both are necessary.

    My point was that both are necessary, a theory with a hypothesis and no experimental results is unfinished - it certainly isn't science.

    My other point was that, since you admit there is at least one "missing piece" in GR, why can't you see that there is the possibility for others. The possibility does not have to mean that all the other evidence for GR is wrong, just that it might need refining.

    Stop being condescending.

    Sorry, I was blindly following suit.

    it is unproductive to assume major revisions unless evidence forces you to.

    I am suggesting that the presence of singularities in the current theory is that evidence. Oddly, you seem to agree.

    If you want to continue this, email me but I need to get some work done today.

    TWW

  • We're quite careful with using correct terms here, aren't we? For example, we don't like that crackers 'steal' the 'hacker' name. So please note that we SF fans hate that our stuff is called 'SciFi'. What Analog writes about is SF, not SciFi. As Isaac Asimov put it, '"Godzilla" is SciFi'. TA
  • It certainly is science. It is an untested scientific theory.

    Nope, t'isn't. Unless you take "scientific theory" to be incredibly wide so that "unexplained cot deaths are caused by the existence of flying fish" is a scientific theory.

    I stand by what I said; a theory with no experimental results just so much hot air. Can you give a counter example?

    As to the rest: I think you'd be better of in some religion of some sort; you seem inordinately protective of the "high priests'" exclusive right to speculate on the nature of the universe. Indeed, all I really said was that I've never liked the existence of singularities in GR and that there is no evidence for event horizons (black holes) that separate them from some other type of super-dense object. You say there is, and I'm prepared to take your word for it for now (some references would be nice, if you have any handy). But still, hardly a hanging offence.

    But you are still replacing one speculation (GR's treatment of space time at or within EHs) with another (that gravity must be quantum).

    In fact there is some reason to think something is going on which might be described as "unknown physics": there have been results over the years which cause some unease. I'm thinking mainly of the slowdown in Voyagers I & II and the recent supernova data, although I dimly remember some strange results from a deep ice bore in Greenland many years ago. Alternative explanations have been put forward for these things but I'm not under the impression that it's all cut and dried.

    bunch of insulting and naive claims about what scientists think,

    I suggested that some people have an interest in keeping theories in which they are experts alive. This happens all the time in science, just as analogous things happen in any sphere of human interest. There is always an orthodox view which will defend itself irregardless of the rights or wrongs of the situation. Science is actually quite good at over-coming this human trait, but it's hardly immune.

    TWW

  • Einstein never even knew that his theory suggests that quantum singularities (black holes) exist.

    Einstein lived to see Chandrasekhar's work and others which covered singularities.

    And Hawking showed that black holes must produce visible radiation,

    If they exist.

    Sorry to be terse but I'm at work.

    TWW

  • Very interesting research (Score:3)

    by Troed ( 102527 ) on Sunday May 14, 2000 @04:54AM (#1074161) Homepage Journal
    ... and if it would prove Einstein wrong, it wouldn't be the first time. Einstein was a truly great scientist, but only human. Especially this list (quote):

    The advocates of the Yilmaz theory list the following additional advantages (not discussed further here) of the Yilmaz theory over conventional GR: (1) it predicts a definite stress-energy tensor while GR does not; (2) it provides exact solutions for gravity waves of arbitrary field strength while GR does not; (3) it has a true Lagrangian while GR does not; (4) it implies Einstein's equivalence principle, while GR must take equivalence as a separate assumption; (5) it is quantizable while GR is not.

    .. makes me want to see more research into this area. The only problem I have with it is that it would invalidate much of Hawkings work ... it would be a shame to see so much of his brainpower having been wasted on false presumtions!

    PS: When I read the article, their counter was at 340. Next refresh displayed all zeroes ... poor website.

  • It is no secret that General Relativity (unlike Special Relativity) is considered by many physicists to be at best an incomplete model. It's good to see some physicists like Yilmaz are taking the time to develop an alternate formulation. They're going to have to meet an awfully high standard of predictiveness and elegance, though, considering the amount of intellectual wealth already invested in the current model. It would have been nice if the article had gone into more detail.

    "When I'm singing a ballad and a pair of underwear lands on my head, I hate that. It really kills the mood."

  • All well and good, but... (Score:3)

    by Dopefish ( 33181 ) on Sunday May 14, 2000 @04:57AM (#1074163)

    This article makes some good points, but some fairly invalid ones. Maybe it's just the way he explains.

    Mathematics doesn't "blow up" at singularities -- it's merely a place where every known equation we have that deals with GR gives us an answer of infinity. Now, this is a problem that's occured in mathematics for centuries, and people have solved these problems for centuries (L'Hopital's rule, for one)

    Well, if Black Holes don't exist, we're sorta screwed. Not necessarily screwed, but it does flush about 60 years of decent cosmological physics down the drain. I guess that's happened before.

    It comes down to who you want to believe, I suppose. Neither side of this argument has barely any evidence of what they're claiming, so, what sounds better to you? :)

  • You'll probably scoff and write it iff as 'mass hallucination', even though psychologists know of no such mass phenomenon.

    Errm, yes there is - the phenomenon of "ergotism" caused by the ergot in rye grains. The ergot is closely related to LSD IIRC, and there have long been incidences of whole towns succumbing to mass attacks of ergotism, including all of the same symptoms as taking LSD. And trust me, I've seen wierder things than the sun dancing across the sky when I've taken LSD :)

  • Re:Scientist are not always right ... (Score:3)

    by zCyl ( 14362 ) on Sunday May 14, 2000 @07:34AM (#1074165)
    Before you bash Hawking (Yes, there's a 'g' on his name) maybe you should get to know the guy first. He's a brilliant, charismatic, humorous guy, and he's perfectly ready to admit he's wrong when shown to be so by evidence. Hawking has said some stupid things (stupid relative to the level of brilliant science he usually produces) in his life, and he has been quick to throw out erroneous work when he was shown to be wrong.

    People like Hawking, if confronted with a suitable replacement for GR (not necessarilly saying this is suitable, obviously there were no mathematics in this pop article), will jump on-board the new theory, excited at the chance to learn and demonstrate new things about existence. It's the pursuit of truth that drives them, not the glory.

    Maybe you could learn a thing or two from them about pursuit of truth... It has nothing to do with what you believe to be true, it has to do with what you can determine to be true. Belief can still exist, it isn't a problem, but if you believe something that contradicts what is in front of your face, then maybe what you believe needs minor adjustment.
  • Removing singularities from the theory of gravity does not necessarily remove the possibility of black holes.

    If there exists a region of spacetime with a field strength high enough that the escape velocity was greater than that of light, then an event horizon would exist. By the arguments backing up the cosmic censorship hypothesis, and the "no hair" theorem, it doesn't matter what is inside the event horizon, as the only observable features of a black hole are it's mass, angular momentum and electric charge.

    If this alternative theory has allows event horizons to exist then black holes still exist, although with different limiting masses. I don't know the exact details of the new theory, so I can't check if event horizons are possible under it.
  • As an extension my last post, the existence of an event horizon would keep most of the work of Hawking and Penrose on black holes, as most of their work is about the properties of the event horizons, rather than the singularities in black holes.
  • This column was written and submitted 10/19/99 and is copyrighted ©1999 by John G. Cramer. All rights reserved. No part may be reproduced in any form without the explicit permission of the author.
    I do appreciate people mirroring slashdotted sites, but we really ought to pay attention to the author's copyright. Ignoring the copyright notice on the page is a lot like ignoring the GPL notice at the top of a source file.
  • When maths predicts infinity its always time to re-examine your formulae.

    Einstein's attitude to this seems to have been that when we reach a certain point in GR the system goes beyond the maths he was using.

    The mistake many people who came after him have made is to assume that the "bizzare" results (eg black holes) reflect reality rather than a break down in the treatment. I personally doubt that Hawkings (who's rep is based on black hole theory) has ever contributed anything to science other than some popularity. Popular and wrong is still wrong.

    It's a bit like assuming that FFFFFFFF + 1 really does equal 0. Until you get a 64bit machine and then you wonder why "reality" has changed.

    TWW

  • PS: When I read the article, their counter was at 340. Next refresh displayed all zeroes ... poor website.

    It just wrapped arround after being /.'ed
  • Evolution has been observed. If you meant to imply it *might* not happen, you might as well be hammering your foot into your mouth anyway.

    As people below have stated, scientists are willing to throw out hypotheses reasonably proven to be false. You won't throw out anything in the Bible. It's a human fault to obstinately have beliefs; you can't claim that being devoted to an organized religion doesn't close your mind somewhat by saying "everyone has beliefs that they won't let go of".

    Religion has purposes other than explaining what science can't. It defines standards of behavior towards others, for example. I consider myself a religious atheist - I behave (relatively :v) ) strictly according to the principles I define for myself, but do not believe they are enforced by a God. I don't expect any ultimate & universal reward for my good behavior. Isn't that more sincere than only "doing it for the money"? But I digress...

    Making arguments that you know won't be accepted or seriously taken, for the purpose of producing responses, is also known as trolling. Jes' a warning to ya.

    Ramble on!
    mfspr r3, pc / lvxl v0, 0, r3 / li r0, 16 / stvxl v0, r3, r0
  • Mathematics doesn't "blow up" at singularities -- it's merely a place where every known equation we have that deals with GR gives us an answer of infinity

    Puh-lease! "Blow up" is a technical term that means exactly what your "correction" says. If you wanna correct this guy, you're also going to have to do some heavy eraser work on Feynman's writing, since he seems to be a fan of that expression as well.

    Anyway, you're either feigning ignorance or you haven't read very much pop-physics (which this is). even authors in PT (physics today) like to talk about equations "blowing up" at certain places.

    cheers,

    sh_
  • Einstein also didn't believe in quantum entanglement, despite laying some of the foundations for QM,

    I understand that a lot of work has been put in on using this for quantum cryptography and this has been used to communicate over distances of at least 40km.

    Disagreeing with the predictions of your own theories on aesthetic grounds is fairly normal, especially when the theory is revolutionary, and you are worried that you might be wrong.
  • <a href=http://babelfish.altavista.com>BABELFISH!</a>

    Ramble on!
    mfspr r3, pc / lvxl v0, 0, r3 / li r0, 16 / stvxl v0, r3, r0
  • Once upon a time, general relativity was a scientific theory with no experimental results. Does that mean that Einstein wasn't doing science?

    Not true: there were observational results which Einstein was trying to encompass, in this case the results came before the theory.

    I never said a single thing about anyone's exclusive right or lack thereof to speculate on the nature of the universe.

    Your dismissive attitude to "laymen" says otherwise.

    Actually you said a lot more, including the insistence that scientists refuse to consider the possibility that GR may be modified at event-horizon level curvatures, or really that they are unwilling to consider alternatives to GR.

    I didn't say that-I may have suggested that some do and that you in particular had a problem but I never generalised to the degree you suggest.

    At least this theory is motivated by an enormous body of evidence in the quantum nature of matter.

    It is indeed, which is why I think it's true. But, as you said, evidence for the quantum nature of gravity is still out of reach. It is mearly a thought (perhaps its a scientific theory) that the reason it's been so hard to prove is that it's not true. Perhaps. But doubtful. Remain calm.

    "scientists are so sure they're right about event horizons, they never consider the possibility they're wrong".

    Don't put things in quotes unless they're quotes. I never said this. I said something similar in reference to some scientists.

    Pioneer (not Voyager)

    Yes, I think I was confusing an article about Voyager's range data being used to put a limit on the cosmological constant.

    I suggested that some people have an interest in keeping theories in which they are experts alive.

    Actually you didn't, though it is true.

    What did you think I meant when I said "I know there is a lot of grant money (and book money) based on assuming there is nothing more to be learnt about these objects,"?

    an interest in keeping's one's theory alive doesn't translate into an orthodoxy that refuses to consider evidence.

    That's why physical sciences are better than most human fields in getting over dogma. Maths is even better.

    What you did suggest was that it is a mistake to consider results to reflect reality merely because they seem "bizarre"

    I was referring to purely theoretical results, not experimental results, although they can lead into trouble too. The danger here is a human one: bizarre results = publicity = grant possibilities and or status (if right). Ask Fleischman and Pons (at least one of whom got a well paid job in Japan to follow up on their data).

    that many "mathematicians" think that bizarre results (presumably event horizons) are a "breakthrough" (I think this is funny,

    I was being glib, so it was supposed to be a bit funny, but there are cases when it happens (the magical neural net for the travelling salesman problem, for example) but actually I meant singularities.

    that physicists accept singularities because duh, they can't think of what else might happen in a collapse,

    It's still true - simple extrapolation that leads to a bizarre (there's that word again) result should be treated with a lot of caution. Extrapolation should always be treated with caution. I seem to remeber Mark Twain commenting on the fact that, given the rate at which the Mississippi delta move upstream each year that 2000 years ago it must have stuck 300miles into space.

    that making speculative hypotheses is "deeply unscientific" (when in fact it's what theorists have been doing all the way back to Galileo, Newton, Kepler, etc.), that hypotheses are "hunches" and not scientific (every scientific theory is by definition based upon hypotheses, not all of which are usually confirmed by experiment at the outset

    It's a question of degree, I think. A hypothesis (eg the anthropic principle) which can not be tested should be treated differently from one which can. Obviously there is a spectrum from "scientific hypothesis" to "pure hokum" (after which is astrology). At some point "speculation" becomes "guessing" becomes "making it up as you go along". I over generalised this point but I do believe there is a distinction and lack of evidence is a bad sign, although not always fatal.

    That my statements about how science is done (and always has been done since the scientific method was formalized) represents a "return to dark-age dogma",

    Well, I still think that your statement that "physics is more or less complete ... is a fairly necessary working assumption in science." is putting the case too strongly. Everyone stands on the shoulders of giants for particular experiments but in the wider scheme of things this is a dangerous assumption and it lies on the road to dogma.

    that I refuse to admit the possibility that GR could be wrong in ways other than those attributable to quantum gravity

    You do seem fixed on quantum gravity as being inevitable.

    that scientists (or some subset thereof) are to be considered dogmatic "high priests", etc.

    You're saying they (the subset, that is) are not?! Go to paleontology, there's piles of them! Physics has it's share too. You must have met some at least.

    In other words, you made a lot of claims and insinuations that (a) show a naive view of how science is done and what science is, (b) are insulting to practicing scientists, and (c) have no basis in fact.

    (a) I have a realistic view of how people work, scientists or not, and I know what science is about and why is is carried on the way it is. It may not be perfect (because of imperfect people) but it's pretty bloody good. (b)some practicing scientists could do with an insult or two. Deny it if you can. Most are "good guys" getting on with valuable, worth-while work. Some steal, lie, and cheat. My own field (computing) has suffered from a few fraudulent results in the name of getting grants. (c) Its just part of life. The alternative is to have no science at all.

    Time to feed the dog.

    TWW

  • A final go:

    I don't know of any specific gravitational physicist who will not admit that GR could be wrong.

    I'm not talking about GR being wrong, the issue is applicability. I'd be astounded if GR was to be proved just plain old wrong. Not universally applicable, I could cope with.

    I don't think singularities are a problem because they're "bizarre". There are plenty of bizarre things that are true. I think they're a problem because they are a literal breakdown in the theory -- physics fails to make predictions.

    Er, wasn't that my original point - that they are a literal breakdown in the theory rather than being a reliable prediction of the theory? I'm sorry I ever mentioned my musings on the event horizons.

    I would be interested to see if you can produce the name (and relevant quotation) of a physicist -- a contemporary would be the most interesting

    Well, I don't actually know your name. Joke.

    We have libel laws in this country and I'm logged on but the specific example I had in mind when I wrote that is one of the people you mentioned, was a big fan of the steady state, and had a run-in with Hawkings at the Royal Society in the days when Hawkings could still walk and speak unaided. I assume that's enough for you.

    Not really comtemporary any more, I admit, but that's who I was thinking of.

    Losing one's temper in a debate is a sure sign of the "high priest" mentality, regardless of how one is treated by colleagues .

    This has been an interesting display of why newsgroups are better than /. for debates; I'm sick of typing into this little box.

    Hope you can reply one last time, but I don't think there's much else to say on this topic, especially as we seem to agree on all the important points of the physics and disagree on most of the human issues. Perhaps I've just met too many bent scientists for my own good. Or perhaps you haven't met enough.

    TWW

  • crypto_creek is always talkin' about a Santa Claus God... WTF? Problem?

    Look here [slashdot.org] for more:

  • These claims sound odd and probably wrong (Score:1)

    by Anonymous Coward
    Some comments from the GR perspective: first, people who study GR don't actually consider conservation of stress-energy to be a problem; rather, this is a feature to be expected (and of course has no conflict with experiment); see the FAQ on energy conservation in GR [corepower.com]. As far as I can tell from the article, it sounds like these guys are saying "energy is nonintuitive in GR and therefore wrong", or they don't like the fact that curvature couples to non-gravitational stress-energy.

    Point 2 is odd, I don't understand what they mean by saying that there are no exact strong-field solutions for gravitational waves; certainly you can have very strong-field solutions like black holes with gravitational waves propagating around.

    Point 3 appears to be wrong, depending on what one means by a "true" Lagrangian; GR is derivable from the Einstein-Hilbert action and has a very simple Lagrangian, that of the Ricci scalar plus whatever matter fields are around.

    Point 4 is wrong. GR does not take the equivalence principle as a separate assumption. It follows from the simple fact that gravity is described by the curvature of a 4D manifold. The equivalence principle really states that "over a local region, spacetime acts Minkowski" -- all that stuff about elevators "in empty space" or "on the surfaces of planets" follows.

    Point 5 is extremely questionable. While it is true that GR hasn't been quantized, there are many approaches to doing so -- such as Hawking's Euclidean quantum gravity, the loop quantum gravity approach, etc. And GR has been quantized in dimensions other than four, at least.

  • <I>Heisenburg's uncertainty principle states that the position and momentum of a particle or object cannot both be known to arbitrary precision. Surely this means that the singularity would be "smeared out" somehow?</I>

    This don't save your day. Both cannot be known with arbitrary precision - but you may indeed measure one of them with any precision you want, screwing up the other one in the process.

    So you can measure the position of your singularity with near-infinite precision, and then wonder what way it went as a result of this measurement.
  • There was a scene in Star Trek: The Motion picture where Decker says "It must've fallen through what we used to call a black hole."

    So we'll just have to start referring to singularities, if they exist, as "what we used to call a black hole."

    I've gotta drive what we used to call a horseless carriage home now.

    ----

  • There's one way to tell who's right. A showdown at the Not OK Coral. :) Seriously, this new version of GR automatically predicts that Hawking Radiation does NOT exist, as Hawking Radiation is a consequence of an event horizon. Professor Hawking's interpretation -DOES- predict this radiation, as a direct consequence of the laws of thermodynamics, as applied to Black Holes.

    Therefore, if JUST ONE of these X-Ray sources produces HR, then GR as-is stands. If none do, it may spell the doom of classic GR.

  • If you were to study a field called "philosophy of science," you should come to understand that whereas scientific theories can be "supported" or "not supported" by evidence, the words "true" and "false" do not apply to them... Actually, a theory can be said to be false, if evidence can be found to disprove it, but we can never ultimately "prove" any scientific hypothesis or theorem. See, science is inductive (whereas math and logic are pretty much deductive), which means something different could always come up in the NEXT experience, and then all our previous experiences have to be re-understood.

  • It is true that a falling object takes an infinite amount of coordinate time to cross a (Swarzschild) event horizon. For an observer in the asymptotically flat regime (that is, an observer 'at infinity') coordinate time is basically identical to proper time, the infall would indeed take an infinite amount of time from such an observer's standpoint. That's not the whole story, however. Radiation emitted from an object falling into a black hole will be gravitationally redshifted, and the rate of emission will be slowed by time dilation. Beyond a certain point the object will be undetectable to the outside world, and at that point the object has, for all intents and purposes, fallen into the hole. I haven't done the calculation in several years, but if memory serves the 'vanishing time' for a collapsing neutron star is very short, on the order of a few seconds after the collapse starts.


    -rpl

  • You are correct, GR and QM are inconsistent with one another. This has been the great embarrassment of 20th century physics; the two great theoretical advances of the century, both backed by mountains of experimental evidence, cannot be reconciled. The usual assumption is that discovery of a quantum theory of gravity will reconcile the two theories.


    -rpl

  • I tend to thing of Science explaining HOW the universe works/exists, and religion explaing WHY the universe exists/works. ;-)

    Thats fine, as long as you acknowledge the possibility that the answer to the "why" question is that there could very well BE no "why", that a mechanistic universe is all there is. I know that possibility upsets a lot of people, who typically respond with a "then what is there that gives our life meaning?" type question. But, to be totally honest, we have to acknowledge the possibility exists.


    ...phil

  • The gods are real. They just aren't what you think. Just try to explain Jungian Archtypes to a child, and the reason for this will become obvious.

    I tried explaining them to my cat, but she just looked at me like I'm on drugs or something...

    --

  • You must mean: Viola!

    Surely you must mean: Voila! ?
  • A wormhole is a black hole which you fall into and re-emerges somewhere else in space before you could reach its singularity. (to use layman's terms)

    Still a black hole.
  • actually, I did the math, and my pencil blew up.

    Ramble on!
    mfspr r3, pc / lvxl v0, 0, r3 / li r0, 16 / stvxl v0, r3, r0
  • In "A Brief History of Time" he says that, according to the theory of GR, in imaginary time, the Big Bang (or any other singularity) looks just like any other point. However when this is looked at in real time, the singularity is still there.

    It is known that general relativity breaks down on timescales shorter than the Planck time, and quantisation effects begin to be large enough to affect results. General relativity doens't apply here, but whatever goes on after this time is indistinguishable from a Big Bang.

  • Re:Slashdotted... (Score:2)

    by Anonymous Coward
    Yilmaz also claims that it can be quantized and that, unlike GR, it reduces to Newtonian gravitation and mechanics in the weak field limit

    It's been a little over a year since I was reading GR, but I seem to remember that GR produced the Newtonian Field equations in the weak field limit... that would, of course, have been one of the first tests to see if it was "correct."

    And everybody should remember that their are pretty large egos on both sides of this argument: those that want to validate many years of research, and those that want to be on the side that "corrects Einstein."

    I will say that the argument presented here is generally saner than most, since they are pointing out that all they are doing is making a minor chnage in the assumptions of Einstein... but I would believe that those assumptions are well justified and have been checked/rechecked many times over the years.

  • In my opinion, with not really knowing GR, black holes are likely to be real, yet i cant believe that for 30 years, so many scientists are still wrong, and i think that who is wrong is that group of scientists, who claims it doesnt exist. Besides, in the article itself they say that weird math brings us to infinity numbers and such, they find it wrong, i dont, infinity number is still a number, and if they bring it as an argument to break theories, i find it queer. Black holes are real, it's reasonable, and it cant be that Albert was wrong...
  • Analog is the most important magazine in the genre. It first published Asimov! It was the home of too many writers to count for decades!
  • I'me sorry, I should've used the word 'Theory' instead of 'Theorem' (English isn't my native language, an error on my side). I study computer science and I had to prove a lot of theorems, so you are right when you say that a theorem is based on logical deduction. What I meant was a theory that is based on (subjective) data and that never can be proven the way a mathematical theory can.

    It's interesting that you claim:
    Evolution has been around for 150 years and itself has been a continuously evolving theory, changing as more information is uncovered. Somehow, however, the basic idea (that species arise from differential change within other species) has stood the test of time.

    It looks like your main argument here is: "It has been around for over 150 years (don't forget that a lot of theories are based on correctness of the evolution theory!) so it's propably correct". I can understand that, but you propably didn't really 'dive into' the matter. I did, and I found a book (written in Dutch by a guy named Peter Scheele) that poses a lot of question by the evolution theorem. Some of the questions were really good founded. They implicated that the entire idea behind macro-evolution (that mutations can eventually cause grow of genetic information) is false.
    During the discussion I had with atheists about this topic, I was amazed that they reacted with some kind of religional arguments. They just couldn't stand the idea that the evolution theorem could be false in a way that meant that there is a Creator.

    My only point here is that far to many people take basic ideas like the evolution theorem for granted (but in fact they ARE NOT proven and still based on (maybe false) deductions over (subjective) data).
  • I didn't really want to bash a specific person, but I took Hawking because he is one of the people that have spended lots of time on blackhole research. I won't argue with you about his intelligence, I have also read his book 'The Universe' and I agree with you that is is a brilliant man.

    Maybe you could learn a thing or two from them about pursuit of truth... It has nothing to do with what you believe to be true, it has to do with what you can determine to be true. Belief can still exist, it isn't a problem, but if you believe something that contradicts what is in front of your face, then maybe what you believe needs minor adjustment.
    I agree, but this counts for scientists as well as for religious people (and for religious scientists :-) I have not yet encountered a theory that posed real problems for my belief. (Please read my other posts about evolution, I wont put that here again). If I encounter one, I will spend lots of efforts to falsificate it, just as every scientist that thinks that the theory is wrong.
  • I hope this theory proves to be right. It should be interesting to see a generation that has been force fed the Big Bang be forced to pass it and swallow something new. ("From the guys who brought you The Big Bang Theory then told you it was wrong, here's the newest in origins...").

    Many of us understand that scientists consider it to be a success when they prove themselves wrong, but the public in general may just drop their faith in the men of science and turn to religion.

    People turning away from science because they don't understand what it's all about. What a sad idea. There should be more education as to what the *point* of science is, the scientific method, and the fact that science *advances* when it proves itself wrong.

    Science is *nothing* like religion and people should stop looking at it like it is. "Faith" in the men of science!? Whaza!?

    -------------
    The following sentence is true.

  • That's not quite correct. As a star collapses, it would be subject to time-dilation resulting from its own gravity. This effect, however, would only be apparent to someone close enough to the dying star to be affected by its strong gravitational field. To observers at a safe distance (say, on Earth), time flows normally and the star disappears beneath an event horizon. (An observer on the surface of the star would indeed have to wait an eternity to see the black hole form.)
  • I'm wondering if any physics geeks out there know if this would effect the 'ol problem of infinite energy required to move infinite mass as the mass approaches the speed of light. This sounds like another one of those places where physics equations "blow up" to infinite values, and this new theory purports to try and remove things like that.
    I really don't know much about physics, i'm just trying to figure out if this could work to the advantage of a sci-fi plot that required spacecraft to move from star to star in less than a few centuries.
  • My post was not flamebait. I resent the fact that it was marked -1 flamebait.

    The problem with moderation is that it oppresses unpopular views.

    My Karma is now negative because I expressed an opinion some people didn't agree with. Well, why don't you clever moderators explain how the 3rd Secret of Fatima does, in fact, refer to the assassination attempt. You can't, because the facts have been distorted to a ludicrous level in order to make it "fit". There is no logical connection between the two, only irrationality. Explain why the Catholic church did not protect the pope - you can't because the prophecy was applied to the event after the fact with no substantive logical reasoning.

    -pitmaster
  • Saying GR overthrew Newton is like saying the Pentium overthrew the 486.

    GR makes the calcuations a whole lot harder, with negligible practical difference except in extreme situations (high speeds or high gravity).
  • Logical Positivism has long since been abandoned as a vaild philophical idea. Why? Because it fails its own criteria.

    "If you can't observe and deduce it, you can't say anything about it at all with certainty."

    I can't observe or deduce anything about "logical positivism" therefore nothing can be certain about it. What a worthless concept. I guess you must have missed this day in PHIL 101.

    Too bad this is an old article and the discussion is dead, oh well.


    --------
  • This article contains several factual errors. Presumably this is a case of the 'telephone game', where the Analog columnist is incorrectly reporting the physicists' claims. However, some of them still trouble me.

    Even the recent Type 1A supernova observations that are taken as indications that the vacuum itself contains energy (see my column in the May-99 Analog.) have not required a modification of GR. Einstein anticipated the possibility that space contained energy and introduced the "cosmological constant" in the theory to account for it.

    Einstein included the cosmological constant to create a long-range force opposing gravity. He did this to make a static universe possible. In this respect, he just missed predicting the expanding universe long before it was observed. Also, it is not correct to say that the Type Ia SNe results have not resulted in a modification to GR. Hardly a week goes by that there isn't a paper on astro-ph describing a time-variable cosmological 'constant' of some sort. It is too early to tell what effect these proposals will ultimately have on our understanding of GR.

    The exception to this rule is the gravitational field itself. While there is energy stored in the gravitational field, unlike all of the other known energy fields (the strong, weak, and electromagnetic interactions) the energy present in gravitation does not, in conventional GR theory, produce space curvature.

    This statement is patently untrue. The gravitational energy does not appear explicitly in the stress-energy tensor, but it still contributes because Gmu nu is nonlinear in derivatives of gmu nu. Indeed, if memory serves, people have constructed solutions to the vacuum Einstein equations in asymptotically flat space that have a nontrivial metric. If so, that would be an example of a gravitational field produced solely by gravitational energy. In fact, gravitational waves in free space might qualify, but I'd have to ponder it for a while to be sure.

    Another well-known problem with GR is that many of its solutions have space-time "singularities", places where the mathematics "blows up" to give infinities in certain physical quantities. An example of this problem is the event horizon of a black hole, where time "freezes" at a certain distance from a super-massive object.

    The event horizon of a black hole is a "coordinate" singularity, which means that it can be gotten rid of by a change of coordinates. (The pole in a polar coordinate system is another example of a coordinate singularity; there is nothing special about the pole in cartesian coordinates.) In Penrose coordinates, for example, the event horizon is well behaved. It is because of this that we know that a particle can cross the event horizon in finite proper time. The center of a Schwarzschild black hole, on the other hand, is an "essential" singularity, which means it really does represent a point where the theory breaks down. Getting rid of "coordinate" singularities is no fantistic feat. I hope this is just something that the author bungled.

    For stars of about the mass of our Sun, the collapse process is halted by nuclear forces, and after the supernova explosion a neutron star is left behind.

    The sun will most likely neither have a supernova explosion, nor form a neutron star. The sun is expected to end life as a white dwarf.

    In this context it is interesting that recent fast X-ray observations suggest a neutron star with about 2.3 times the mass of the Sun. This is a very large mass for a neutron star. It is at the very outer limits of what standard GR can accommodate and requires considerable tinkering with nuclear forces at high densities to make it possible. This is not definitive evidence, but it does tend to provide some support for the Yilmaz theory.

    The nuclear equation of state is very poorly understood, so a little "tinkering" (or even a lot) is to be expected. To me, this evidence is better taken as a constraint on the nuclear EOS than as evidence against GR. If arbitrarily massive (non-black hole) compact objects are allowed, then where are the 5 or 10 solar mass neutron star--like ojbects? For that matter, what holds them up? Degenerate neutron pressure has to fail eventually because the pressure contribution to the stress-energy tensor outstrips the pressure forces' ability to resist gravity. Since their theory claims to include an explicit gravitational contribution to the stress-energy tensor, I would think that the tendency would be to make this problem worse instead of better.

    it provides exact solutions for gravity waves of arbitrary field strength while GR does not.

    This is not a statement about physics, so much as it is a statement about mathematics. We can't (usually) solve the GR equations in closed form. Big deal; the same is true of quantum field theory. Surely he doesn't mean to claim that solutions don't exist for strong gravitational waves in GR.

    it implies Einstein's equivalence principle, while GR must take equivalence as a separate assumption.

    I don't understand this claim at all. If this theory is a metric theory of gravity, then it builds the equivalence principle into the theory in the same way that Einstein GR does; viz., by making the equations of motion depend on the metric.

    Several critics have published detailed criticisms of the new formalism and its interpretation.

    I am beginning to see why; the more I read about this theory the more skeptical I get. It would be interesting to see what the criticisms were; pity the author didn't give them a few column inches. Maybe there are references in the original article.


    Not holding my breath,

    -rpl

  • Off course what everyone wants is a GUT (grand unified theory) that works. GR appears to be compatible with some string theories (although they also require SUSY

    I've got it ! Just use DEBIAN instead and we will solve the world!

  • `` if you want to read some rousing good Hard SF novels, read John Cramer's TWISTER and EINSTEIN'S BRIDGE. Good stories, good characters, good science.''

    After being a hard core science fiction reader for years (and years, ...) I'd gotten pretty fed up with the genre in recent years. The two novels by Cramer got me back to reading it again. The chapter in Einstein's Bridge where the alternate universe breaks through into the Super Collider tunnel still creeps me out sometimes when I think about it.
    --

  • not really "no black holes" (Score:3)

    by TheDullBlade ( 28998 ) on Sunday May 14, 2000 @09:21AM (#1074207)
    Most non-physicists don't care about what goes on under the event horizon, and would be perfectly happy to call anything a black hole that is heavy enough to have an escape velocity greater than the speed of light at some height above its surface. You still couldn't see them unless something was falling in, they'd still have a powerful lensing effect on light, they'd still gobble up stars and planets, you still would never want to fall into one, and things would still be seriously wierd right near the "event horizon" (meaning, in this case, distance beyond which even light cannot escape).

    Really, they just mean "no singularities," and since singularities are supposed to hide behind event horizons, they aren't really very interesting to the layman. I suppose it also means "no small black holes" (which would evaporate so quickly you wouldn't notice them anyway, except perhaps as a hiccup in the massive blast you'd need to create them with), since without singularities you'd need to pile up enough mass to make an escape velocity over the speed of light beyond the surface of the pile.

    OTOH, maybe we don't need singularities for singularity-like effects. Maybe matter will compress beyond composite baryon structures more easily than we think, and be stable enough to be interesting. Quantum mechanics is still pretty hairy, and I don't think we know as much as we think we know.

  • Alternative Formulation of GR (Score:5)

    by efuseekay ( 138418 ) on Sunday May 14, 2000 @09:30AM (#1074208)
    Interesting, but people have been trying to "extend" GR for years. Prof Yilmaz is probably not the only one around. Here is a summary of why GR is so troublesome to many people : (a) It is not a gauge theory. Which is irritating to physicists because the rest of the other forces (weak, strong, electromagnetism) is. Basically a gauge theory takes some form of "particles/fields" (field is the correct word, but people seem to be familiar with particle more), impose some "geometric" constraint on it (i.e. the curvature thing Cramer is talking about), and Walla! You get the equations of motions, eg. the Maxwell equations for EM etc.. The point is that all the other forces are DERIVABLE from some consideration, which led physicists to believe ALL forces must be a gauge theory. But GR is not. Now in a Gauge theory, one can derive the Stress-Energy tensor by using Noether's Theorem. Why is this S-E thing so crucial? Well because the S-E tensor basically says Energy/Momentum/What-have-you is conserved! Yes, another surprise : Conservation of Energy is DERIVABLE from a gauge theory. It is not some "fuzzy concept" we impose arbitrarily. But in GR, we can't do that. So we can't impose local conservation of energy. People are disturbed by this... That's why physicists wanted nice "gauge theories" . Now, having said all that, it is conceivable to "extend" GR, by basically adding more "terms" in the equations, take make GR a gauge theory. This is what probably Yilmaz has done (i've not seen his papers, but I will bet my library on this). OK, the get nice gauge theories and such....BUT why add more terms?? This question is begged to be asked. They say : so it's a nice Gauge Theory! But we say : but that's cheating! The solution : make observations. The observations : nah....Black Holes probably exist. (b) GR is not renormalizable. "Renormalization" is just a big term to indicate that we can "get rid of the infinities" by some trick. Now Renormalization is a big thing to physicists : it makes equations nice and "well behaved" (literally). Physicists/Mathematicians know how to renormalize Gauge Theories (a few Nobels have been awarded for this great breakthrough, Feynman/Schwinger/Tomonoga for QED, Wilson for renormalizable gauge theories, d'hooft and Veltman for non-abelian gauge theories). But GR is NOT a Gauge theory! And people still don't know how to renormalize it. But instead of screaming "no!", physicists embraced the resulting Infinities as "hey that's cool! Look Ma, a Black Hole!". Why? I don't know, probably historical. But IT'S BLOODY HARD TO RENORMALIZE A NON-GAUGE THEORY!!!!! (c) It is not Quantizable. Now, we know how to quantize a renormalizable gauge theory (see : I cleverly organized this article such that everything falls into place :)). But GR is NOT a renormalizable gauge theory! So we don't know how to quantize it! Thus we are in a time in the history of Science that we are stuck. Unless we do things like Yilmaz, by arbitrarily adding terms to the equations (for those physicists out there : we add extra couplings to the Lagrangian), we are left with either accepting that GR is just DIFFERENT from the rest of the world, OR, that we just have an incomplete theory. Physicists, of course, to protect their jobs and grants, say "We have an INCOMPLETE THEORY! GIve us more money!" The current "hot" thing is Superstring. A marvellous piece of beautiful mathematical theory that "may" unify GR and the rest (the so call Super Unified Theory, as opposed to Grand Unified Theory w/o GR). The only problem is, as Cramer said, "it's under construction". He did not mention something more sinister : "Superstrings predict crazy things!!!!" Yeah, like 10^16 GeV particles (an accelerator the size of the Milky Way is needed to make such particles). So SUPERSTRINGS has NO experimental evidence. Here thus, is the current situation in Physics. So, as a wanna-be theorist, I implore you, Slashdotters to : GIVE US MORE MONEY ! WE HAVE AN INCOMPLETE THEORY!
  • It looks like your main argument here is: "It has been around for over 150 years (don't forget that a lot of theories are based on correctness of the evolution theory!) so it's propably correct". I can understand that, but you propably didn't really 'dive into' the matter.

    On the contrary, I've spent the last semester taking a course on the history of life, one of whose purposes is to make a cogent argument for evolution as a theory quite consistent with observation. Note my terms: consistent with observation. There hasn't been a scientific theory yet proposed that is not, for some detail, "false." The purpose of science is not to look for some ultimate truth, it is rather to try and model the processes of the universe. Evolution is a theory which has given remarkably accurate predictions; that is what I mean when I say it "has stood the test of time."

    A few lectures in the course I took focused on the movement in the U.S. to try and produce an alternative theory in some way consistent with the events as literally portrayed in the Bible. This movement seems to have two main tactics:

    a) Produce examples/arguments why evolution cannot be correct.

    b) Produce an alternate theory to evolution which suggests certain parts of the Biblical story.

    The problem is, both these tactics are not science in good faith, because they seem to operate separately within the movement. In order to replace a theory, you must produce another theory that explains properly more than the original theory; in other words, you must find places where the old theory gave bad predictions and your new theory must improve these predictions (as well as predicting accurately everything the old theory did). So "creation scientists" are not acting in good faith when their new theory and their criticisms of the old theory have nothing to do with one another.

    When I say "evolution has stood the test of time" what I mean is that in the 150 years since Darwin came up with his theory, no one seems to have produced a theory which explains as much observed phenomena.

    The issue of whether atheism is a religion is a whole other point. You're absolutely correct in observing that some people seem to believe that the theories of science are "true" in the same way that you probably believe in a G-d. I've thought about this a lot, and I think what atheism comes down to is to making logical arguments based on the axiom that there is no G-d. Some people believe that there is no G-d as fervently as you probably believe there is one. Science, when practiced in good faith, however, is immune from such arguments, because the physical reality of a G-d (in the sense that Its existence can be inferred from physical phenomena) is a scientific hypothesis like any other. As I see it, there is no or next to no evidence for an active G-d, and so I am forced to conclude that the world now operates in a natural (i.e. consistent and predictable) fashion. This does not, however, mean that I am an atheist. I consider myself to be an agnostic, in the sense that believing in a G-d or a lack Thereof serves no purpose in my life, and so I leave the question open. It is unanswerable by scientific means.

    Let me be clear. I think the whole atheism/theism argument is silly--agnostics will not get involved in the discussion, and then all you have left are die-hard believers shouting at deaf ears.

  • The problem is, both these tactics are not science in good faith, because they seem to operate separately within the movement. In order to replace a theory, you must produce another theory that explains properly more than the original theory; in other words, you must find places where the old theory gave bad predictions and your new theory must improve these predictions (as well as predicting accurately everything the old theory did). So "creation scientists" are not acting in good faith when their new theory and their criticisms of the old theory have nothing to do with one another.


    Well, the creationism "scientists" are also acting in bad faith because what they propose is not science per se. That is, what they have produced is not observable nor testable in any reasonable fashion; instead they say "because God (defined as a supernatural, superpowerful being which is beyond the relm of observation or measurement) made it happen, and because God told us so (in the Bible)."

    Well, God (as so defined) cannot be quantified nor measured. So it is impossible to perform any observations or experiments on creationist science as this would require us to measure or quantify God.

    Perhaps Creationism is good theology, but it's crappy science. And like oil and water, theology and science cannot mix: theology (such as creationism) deals in things that cannot be observed or measured by it's very definition, while science deals exclusively in observable and measurable things.
  • Someone should moderate this up -- it definitely deserves comment from people familiar with the law.

    The only difference I can think of is that you can limit the behavior of the search engine bots, to some extent. I don't know if you can control caching, but you are supposed to be able to tell the bots not to index your pages. Not doing so could be interpreted as implicit permission to cache. I very much doubt the law would agree, but I'm sure someone would argue it.

    Come to think of it, the whole issue of web caching on the sever side (e.g., to speed browsing), and possibly even client-side, seems to have been under-addressed. I believe the UK (or EU; whatever) has law on the books, but I can't remember what it says. I could be thinking of the wrong caches, though.

    Then again, while the law certainly doesn't agree (I assume), this doesn't appear to threaten the copyright holder's rights. Google makes it very clear where the page came from and how to get to the original, and this really seems to be beneficial to page owners, given the unpredictable nature of the Web (e.g., server crashes). Maybe caching should be fair use, perhaps as an infrastructure feature.

    -jcl

  • Doesnt Google Cache a lot of websites? Are there Copywrite problems in that case?

    ^Z
  • The slashdot effect is destroying the internet, sucking helpless webpages into a black hole!
  • The only problem I have with it is that it would invalidate much of Hawkings work ... it would be a shame to see so much of his brainpower having been wasted on false presumtions!

    Considering the many successes of the current model, it seems likely that a lot of that work may still be relevant. Any model that replaces GR will be likely to have similar mathematics. It would be nice if the article had explored that.

    "When I'm singing a ballad and a pair of underwear lands on my head, I hate that. It really kills the mood."

  • Re:All well and good, but... (Score:3)

    by MattXVI ( 82494 ) on Sunday May 14, 2000 @05:12AM (#1074240) Homepage
    I don't think much of the last 60 years of cosmological physics depends on the existence of black holes.

    And it is not at all common to obtain a division by zero (singularity) in physics when you are talking about measurable quantities. L'hopital's rule, of course, would be useful when a number doesn't 'blow up', but rather when the expression you use to describe it blows up, giving you a zero divided by zero, instead of the expected, say 'sixteen'. L'hopital's Rule overcomes a problem with the form of yourr expression, but it is useless when the actual number is 'blowing up'.

    "When I'm singing a ballad and a pair of underwear lands on my head, I hate that. It really kills the mood."

  • That's true, but not all of those count as "gravitational fields produced solely by gravitational energy density". In particular, solutions with boundary conditions that force nonzero mass densities in regions outside of the region considered by the solution probably don't count because a reasonable person might object that the field is being caused by that mass "over there", outside the boundary.


    Take the Schwarzschild black hole, for instance. The Schwarzschild solution exludes one point, the singularity, from the solution. Moreover the boundary condition is that far from the hole it "looks like" there is a pointlike mass at the singularity. Most would say that the gravitational field "comes from" the mass hidden away in the singularity. This intuitive view is bolstered by the fact a (spherical) compact object (say, a neutron star) will give you exactly the same field (outside the star, of course). Would we say that a neutron star's field is caused by "gravitational energy density creating a gravitational field"? I think not.


    By contrast, I think a gravitational wave really does represent a gravitational field that gives rise to other gravitational fields without any implied mass, in much the same way as an electromagnetic wave represents E-M fields that give rise to other E-M fields without any implied charge.


    -rpl

  • I'me a christian, and everytime I have a discussion about things like the Evolution theorem there are people that say "You can never be as open-minded as we are, because the truth is already certain for you, and you will never accept anything that doesn't support that". I partly agree with them, but the forget that as atheists, they do exactly the same. There is always one thing they can rely on, and that's the fact that God doesn't exist, so there has to be a theorem that explains our existence. This shows that nobody is completely objective.

    *sigh* I see someone hasn't studied the philosophical underpinnings that make modern science. Okay, let's review.

    Science is a special process first outlined in the principles of logical positivism. That is the philosophy of deriving how the universe works around us through the process of observation, deduction and testing through hypothesis. Logical positivism itself is a descendant of logical objectivism, where one derives how the universe works through observation and testing alone--if you can't observe it, you can't talk about it.

    My point is that logical positivism is not opposed to theism or a theistic point of view. Logical positivism doesn't say "if you can't deduce it, it doesn't exist"--instead, it says "if you can't observe and deduce it, you can't say anything about it at all with certainty."

    Science, as a form of logical positivism, basically inherits this trait. That is, science, being the process of observation, creating hypothesis to explain the observations, and testing those hypothesis to make sure they're true, has nothing to say about the existance or non-existance of God.

    That is, Science says "as I cannot test the existance or non-existance of God, I have nothing to say about God." This is not atheism. This is ducking the question, as any good scientist, wearing a science hat, must do.

    A second truism of logical positivism is that as searching for the truth is the constant refinement of observation, hypothesis and testing, no single hypothesis can completely explain the universe. In fact, the findings of Godel's incompleteness theorm applies here: no mathematically constructed system can be "complete." So it is an inherent truth of Science that no theory is complete.

    However, this does not mean the theories are inherently wrong, or fictions created by a bunch of atheists to deny the existance of God. As I said before, science has nothing to say about God--science has nothing to do with the validity or non-validity of any theological system. (To suggest otherwise is to be an insulting and inconsiderate twit towards the many scientists who are also good Christians, Jews, Muslems and others, but I digress.)

    Much of the uncertainty of the theories that scientists work with have more to do with tweaking the fine points when you reach the theoretical limits of what has so far been observed and tested. The article refered to was basically not suggesting that General Relativity was bullshit--actually, it was suggesting that an additional tensor added to the energy equations expressing the warping of space-time by gravity makes the mathematics more elegant. To suggest that we throw out GR because of a debate over the addition or removal of a tensor factor is akin to suggesting I have the IRS lock you up in jail because you forgot to declare finding a $5 bill on the ground, or suggesting you be excommunicated for the $0.90 in taxes that you stole from the government in direct violation of God's commandments and the words of Jesus Christ.

    Theism is a wonderful philosophical branch, giving firm roots in both our need to find reason in our lives, as well as finding a firm ethical, moral and spiritual ground on which to stand. And this is totally orthogonal to good science--you cannot put a soul in a mass spectrograph, nor can you weigh morality on a balance beam.

    Darwin said in the introduction of a later edition of his "Origin of Species" that it was not his intent to disprove the existance of God. Instead, it was his intention to illustrate the process by which God created us all, and thereby showing us in great detail the hand of God as it moves across creation. It always fascinates me the number of fundamentalist wackos who conveniently forget this fact in their effort to muck-rake, just as it is interesting the number of them who call Catholics "un-Christian" because the Holy See has embrased scientific results of evolution, quantum mechanics and relativity as illustrative of the hand of God in action.
  • There is a large group, larger in some countries that others, who simply says "in the absence of credible proof of a god, we will assume there isn't such a creature untill such time the situation should change" ie, there is a closeminded group who thinks "there must be a god" and a closeminded group who think "there can't be a god" and the big group in the middle who thinks "we'll see what develops"


    Then there are those of us who concede that the presence or absence of God is something that inherently cannot be described by Science, and who thus realize that we must have faith in something that by definition cannot be measured or quantified.

    Most fundamentalists who believe you must either "believe" or "not believe" and who believe that scientists must "not believe" have apparently replaced faith with anger.

    It's rather sad, really.
  • That's an unfair generalization. I was the original poster in this thread and I am 20. I stared reading Analog back when I was 13. I remember very clearly the story that got me hooked. It was by Ben Bova (I think) about the truth about canals on Mars. I think it was in the April 1993 issue. Unfortunetly, I have not read in a long time though.

  • The purpose of science is not to look for some ultimate truth, it is rather to try and model the processes of the universe. Evolution is a theory which has given remarkably accurate predictions

    'The purpose of science' is still open to debate. The one you are advocating is, or is related to, empiricist theories of science, which in turn are closely related to anti-realist theories - ie that there is nothing at all 'in' science aside from predictive powers.

    I am not sure that you are arguing that the sole purpose of these models is for predictive purposes alone, and I don't necessarily advocate the realist view of science - I'm just pointing out it exists.

    Some problems that have been noted with the empirical (ie purely predictive) view of science are that it is difficult to determine the line where the constituents of the model (say 'atoms' for example) and observed scientific phenomena begin (ie 'bacteria', which cannot be seen with naked eye might be postulated as merely an explanatory device for the occurance of disease, or a phenomena in their own right).

    I suspect that you postulate 'organisms' and 'species' as real things that evolutionary theories predict the behaviour of. Some theorists haven't - they have regarded the immediate sensory perceptions of our mind as reality, and 'organisms', 'society', 'sub-atomic particles', 'people' etc as tools to predict immediate sensory phenomena (and then there's the problem of defining what a single, irreducible sensory phenomenon is for the purpose of predicting them).

    Basically, I'm just noting that although many 'working scientists' (who have apparently been placed under the microscope by philosophers) hold an empiricist view of science, there are some who hold the view that science is a quest for ultimate truth about reality, and that current scientific theories are closer to describing that reality than, say, religious beliefs, and that refinement of scientific theories as time passes approximate reality more closely than before. To these people, the development of evolutionary theory in line with their idea of the scientific method, and its contribution to an overall picture of reality might be make the case for holding it as powerful as its predictive powers would.

  • If this is right, it means that there are probably only 4 dimensions to spacetime, not 26 or even 10.
  • Someone moderate this up. The guy seems to know what he's on about.

    Um, it's a reposting of the original article, not a commentary on it.


    ...phil

  • This article might seem very provocative, but it isn't really. Some people say "this undermines 60 years of relativity studies, so it almost can't be true" as an argument for Einsteins GR theorem. This is the WORST attitude that any scientist can have

    I'me a christian, and everytime I have a discussion about things like the Evolution theorem there are people that say "You can never be as open-minded as we are, because the truth is already certain for you, and you will never accept anything that doesn't support that". I partly agree with them, but the forget that as atheists, they do exactly the same. There is always one thing they can rely on, and that's the fact that God doesn't exist, so there has to be a theorem that explains our existence. This shows that nobody is completely objective.

    My point: Some people (like Stephen Hawkins) thank their careers from theorems about black holes or other theoretical astronomical theormens. The outside world looks at them as real (objective) scientists, but when an alternate theorem appears, they are the ones that will fight it the most. Not because the theorem might be wrong, but because they loose all their status in the scientific world.

    I think that a lot of things that are considered to be certain (like the evolution theorem, relativity, quantum effects, etc.) are not as certain as most scientists want us to believe. I hope and pray that there will be more sceptical scientists that put questionmarks by those theorems.
  • And I guess you must have missed your "Philosophy of Science" classes.

    I'm quite aware that Logical Positivism has been abandoned by most philosophers since about the 1950's, for two reasons: one, it doesn't explain itself. Two, as a philosophy which attempts to explain "why", logical positivism falls flat on it's face. It's really quite unsatisfying as a unified system of philosophical thought, given how many questions it leaves totally unanswered, and how much of the very nature of our existance it leaves totally unexplained.

    However, shadows of logical positivism lives on in the scientific method.

    Unlike philosophy, science (and any good scientist) is quite content to side-step "why" and concentrate on "how". And science is quite content to leave a lot of questions unanswered, and leave that to the theists and the philosophers. The very limitations which made philosophers abandon logical positivism as a philosophical system cause scientists to implicitly embrase it's methodology.

    And that goes right back to my point that science has nothing to say about the nature of God.

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