Slashdot Mirror
Black Holes Don't Exist???
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."
11 people making completely uninformed guesses starting out with IANAD
4 people complaining that they won't be able to look at Natalie Portman (fake)pr0n anymore
6 people complaining that now, due to lack of sight, can't pour hot grits down their pants
and, last but not least
2 people saying... "Is this news for nerds? Is this stuff that matters? Slashdot sucks lately"
-- Dr. Eldarion --
It's not what it is, it's something else.
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?
If you can write 50 lines of correct Dutch for me then you have point
--
If code was hard to write, it should be hard to read
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).
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...
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.
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.
Aren't you dead?
(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.
-- Virtual Windows Project
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.
-- Don't believe everything you read, hear or think
I can't tell if you're an agnostic or if you're a theist who admits his dependence on faith (which is totally fine, BTW), but I'll throw this out anyway for an agnostic to answer:
How can you assert that God is unknowable if you think that God is unknowable?
(I'm a weak atheist, FWIW)
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!
The salient points are:
In other words, real holes have all of the important features of theoretical holes; they differ only in minor details.
-rpl
Except that the theory proposed claims that there are no infinities... as in no infinite gravitational fields... no event horizons.
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. 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.
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
"These laws they're passing won't even compile anymore, let alone execute." - anon
--
If code was hard to write, it should be hard to read
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.
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??
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.
Aren't you dead?
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.
-- Insert witty one-liner here. --
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.
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?
--
The only thing necessary for the triumph of evil is for good men to do nothing. - Edmund Burke
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":
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
"Encyclopedia" is to "Wikipedia" what "Library" is to "Some people at a bus stop"
[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.
... think of all the SciFi material we have to rewrite now!!!
it's in my head
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 where you will find what are experts objections.
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
"Encyclopedia" is to "Wikipedia" what "Library" is to "Some people at a bus stop"
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
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
"Encyclopedia" is to "Wikipedia" what "Library" is to "Some people at a bus stop"
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
"Encyclopedia" is to "Wikipedia" what "Library" is to "Some people at a bus stop"
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.
PS: When I read the article, their counter was at 340. Next refresh displayed all zeroes ... poor website.
it's in my head
"When I'm singing a ballad and a pair of underwear lands on my head, I hate that. It really kills the mood."
When I'm singing a ballad and a pair of underwear lands on my head, I hate that. It really kills the mood.
-Tom Jones
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 :)
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.
Oh, go on, check out my job.
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
"Encyclopedia" is to "Wikipedia" what "Library" is to "Some people at a bus stop"
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.
: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...
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
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!
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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_
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Ramble on!
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Check out Project Upper/Mute, an all-around awesome compiler fra
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pronoblem
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.
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.
----
----
"I used to listen to Null Device before they sold out."
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.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
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.
-rpl
-rpl
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
...phil
"For a list of the ways which technology has failed to improve our quality of life, press 3."
I tried explaining them to my cat, but she just looked at me like I'm on drugs or something...
--
"Convictions are more dangerous enemies of truth than lies."
You must mean: Viola!
Surely you must mean: Voila! ?
-----------------------
Moderator's essentials
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.
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.
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...
Dan.
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!
It's interesting that you claim:
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).
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If code was hard to write, it should be hard to read
I agree, but this counts for scientists as well as for religious people (and for religious scientists
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If code was hard to write, it should be hard to read
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!?
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The following sentence is true.
The following sentence is true. The preceding sentence was false.
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
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.
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"Every artist is a cannibal, every poet is a thief."
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.
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.
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.
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.
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.
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.
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.
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!
I've *seen* people playing 6D 3x3 noughts and crosses. (what you yanks call tic-tac-toe). Each game used a lot of paper.
I think the objective was to get as many lines as possible (in 3D, the first player can force a line easily, so I imagine it would be even easier in 6D).
To stay on topic -- if you were falling into a black hole, you would need something like this to pass the infinite time that would need to go by before you were crushed
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.
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!
Mode (3) smart-aleck mode. Press * to return to main menu.
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.
It also shows you exhibiting a what appears to be a common prejudice in christians; they seem to think that either you are a christian or you are an atheist - a big fallacy. 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"
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If Google really cared they would fix Android Chrome to reflow text, instead of discriminating
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.
Aren't you dead?
The other theory of relativity is known as "general relativity". This is essentially special relativity, but with space being curved, rather than flat. The curvature is induced by gravitation. General relativity is not universally accepted among cosmologists and theoretically physicists, because the experimental evidence for it is lacking. So Cramer's column is nothing new.
While I respect John Cramer's knowledge on the subject, he prides himself a little too much on his published work and neglects his teaching skills. I took his introductory lectures on Electromagnetics and Oscillatory Motion at the UW, and, unfortunately, I learned more from Holliday and Resnick's Fundamentals of Physics than I did from his course.
This seems to be a common trend at universities: Hiring research professors to bring respect to the college, while forgetting about the needs of the students. Of course, ideally there should be a high correlation between one's research skills and one's teaching ability.
hmm.....that'd actually be awesome....even if it'd have to be a totally mathematical/non-graphical game. But maybe something like chess in 10D?
Grades, Social Life, Sleep....Pick Two.
--Justin Mitchell
"2nd Place is a fancy word for losing" --Bender (Futurama)
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.
Sorry, but this post just wasn't a flaimbait. Maybe somebody didn't like what I said, but it's sad that that person tries to moderate stuff down if he doens't agree with the points
Oh, before I forget, I always thought that a flamebait was a flaimbait if there was a flaimwar involved. Please read the comments, you'll see that it's a perfectly normal discussion.
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If code was hard to write, it should be hard to read
"I partly agree with them, but the forget that as atheists, they do exactly the same."
Consider the difference between "weak" atheism and "strong" atheism. If you don't understand it, then your philosophical education is lacking.
In weak atheism, the atheist asserts nothing: "I do not believe in god."
In strong atheism, the atheist asserts something: "I believe there is no god."
Weak atheism is disbelief, whereas strong atheism puts forth an assertion. The difference, a weak atheist has nothing to prove and, therefore, cannot be disproved - of course, they'll still burn in hell. A strong atheist gets sucked into arguments about the supernatural. That is pointless since the supernatural is impervious to the natural.
http://w ww.google.com/search?q=cache:www.npl.washington.ed u/av/altvw100.html
This is Google's cache of www.npl.washington.edu/av/altvw100.html as retrieved on Sunday, 09-Apr-00 08:37:33 GMT.
# grep slashdot access.log | grep html | sort | uniq | wc -l 2604
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
Concept #0:Consciousness
Einstein searched until the moment he died for the equation of the "Unified Field Theory". He never realized the missing element was the same element that caused so much of his life to be what it was.
From the cheers and recognition from supporters of his work to the threats on his life, exile out of his country and destruction of publications on his work. All this caused from the element Einstein was exercising, but not realizing, the element of consciousness.
It was Einsteins' conscious efforts that lead him to produced his work. The consciousness of those who recognized his work and put forth the effort to honor him for it. The conscious efforts of some to create an illusion, leading many into action of threat, destruction and force to have a physical impact on Einstein and many others. And it was the conscious efforts to apply Einsteins' work that contributed to creating the physical power that removed the force which cause Einstein to leave his country.
Perhaps Einstein did come to intimately know what the missing element was, in those last few moments of his life.
The Spinoza equation "T1 = T2 k" expresses two perspectives: All things in physical reality can be comprehended/translated into conscious thought and conscious thought can be converted/translated into physical reality.
For those who have doubt about the validity of this equation: Look around and note all the physical things you perceive. Then determine, to the best of your ability, what exist as a result of conscious comprehension of physical reality and conscious directed action, effort and intent to apply physical movement to create? In other words: What do you see that originated in conscious imagination?
For those still in doubt: What don't you perceive, but know by what you do perceive, that there must exist both the conscious ability to comprehend physical reality and conscious imagination to cause intentional control of physical reality? (i.e. Computer usage and its internal operations. Software and it's existence on magnetic media. Disease identification and treatment or cure. Radio wave creation used in sending and receiving data, and its' translation to and from what we can perceive - music, pictures of stars we cannot see from earth but now know they exist. The life we create via genetic control and duplication, etc..)
3 S.E.A.S - Virtual Interaction Configuration (VIC) - VISION OF VISIONS!
Maybe you're a dutch jew...
Don't beat yourself up. You did the best anybody could of expected. Better luck next time. Never give up, never surrender.
Is it just me or does anyone else envision the end of "Raiders of the Lost Ark" whenever they see the Pope?
Oh. So it is just me.
Looks like the stupid moderators are too stupid to know that a post refers to its parent, not its parent's parent.
Stupid moderators. Trix are for kids.
He doesn't pretend to be qualified to tell us about God. Any comments he makes are to satisfy the great majority of lamers who reject science because their church tells them to.
Why does Contact come to mind?
Except that the theory proposed claims that there are no infinities... as in no infinite gravitational fields... no event horizons.
But an event horizon isn't an infinity. An event horizon is simply the sphere around a mass at which the escape velocity is equal to the speed of light (c). Closer to that mass, the escape velocity is greater than c, so it is impossible to see any "event" that occurs beyond that "horizon," hence the name.
The Spinoza equation "T1 = T2
By induction, T2 = T3. Now I know who to call when I need that extra bandwidth
Doesnt Google Cache a lot of websites? Are there Copywrite problems in that case?
^Z
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.
So, when can we expect all the world's cache of nuclear weapons to suddenly explode? :P OK,OK, so the research for them started a little earlier than those 60 years...
I guess that's happened before.
Oh, you mean the question about how many angels can dance on the head of a pin?
Some people might complain that gravity should not be counted twice. Some have said that this would result in an infinite loop that would cause an infinite field. However, this is not nescessarily true as anybody who has looked at a geometric series can say. What I am referring to is: (1/2+1/4+1/8+1/16+...) ad inifinitum actually adds up to 2, and not infinity. The Greeks had that problem in their philosophical discussions. In addition, there are many examples of such recursive feedback mechanisms in other fields. Biological models typically experience them. Chemical models have to deal which such things all the time. Physicists who study resonanse and vibrations have to account for vibration feedback in all their calculations.
Good going. Challenge the Masters. Tweek the formulas. I look forward to the results of this debate. As for the fundamentalist comments...they don't have the minds to comprehend anything but simple concepts and Santa Claus versions of God. Ignore them (except when they try to ban the science of evolution from schools, or ban books). They don't worship God anyway but some wierd Demon of Ignorance.
Wovon man nicht sprechen kann, darueber muss man schweigen. Ludwig Wittgenstein
So here's the info:
This column is a milestone. It's the 100th Alternate View column that I've written for Analog over a period of 16 years beginning in 1983. I was on a sabbatical in Berlin when Stan recruited me to write the column after Jerry Pournelle, my predecessor as AV columnist, decided to step down. The AV columns are a soapbox that was too attractive to pass up, and I've used them to promote an interst in science and to feed cutting-edge science ideas, primarily in the areas of physics and astrophysics, to the readers and writers of science fiction.
In this column I want to examine a recent variant of General Relativity that predicts, among other things, that black holes do not exist. General Relativity (GR) was first formulated by Albert Einstein in 1913. Today it remains the standard model for gravitation. Over the past 86 years it has survived many experimental and observational tests and challenges without requiring modification. 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. Most physicists today consider GR to be the epitome of a nearly perfect theory. It was carefully constructed on a foundation of physical reasoning and mathematical elegance, and it has a certain intrinsic beauty. GR sets a very high standard that makes theories in other areas of physics appear contrived and inelegant by comparison.
Nevertheless, a small group of dissident theoretical physicists has recently been pointing out certain problems with orthodox GR and advocating a modification that has interesting consequences. It's this GR variant that I want to focus on here.
In standard GR, gravity is considered to be "geometrical", to be a consequence of the curvature of space produced by nearby mass-energy.. If a mass or an energy-containing field is present in space, GR predicts that the space will become distorted. This distortion or curvature of space produces gravitational effects like the attraction between masses and the gravitational bending of light rays.
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.
However, Einstein's choice of excluding gravitational energy as a source of curvature leads to problems with local energy and momentum conservation. With the exception of gravitational energy, the law of conservation of energy applies to all fundamental interactions "locally" at all points in space. Because gravitational energy does not produce curvature, it does not respect local energy conservation. While energy is conserved in a large volume of space in GR, it is not conserved point-by-point.
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. Inside this boundary is a singular region, a place where mathematics cannot take us. Such mathematical anomalies in the solutions of Einstein's equations are very disturbing. They have been taken by some, including Einstein himself, as a signal that something may be fundamentally wrong with the GR formalism in the regime where very strong gravitational fields are present.
A third problem with GR is that we are sure there must be some comprehensive theory (quantum gravity) that describes gravity at the quantum level, yet orthodox GR theory seems to be incompatible with standard quantum mechanics,. Almost all of the attempts to unify quantum mechanics and general relativity have failed, in part because the singularities of general relativity seem to be incompatible with the quantum formalism. The one exception to this incompatibility is superstring theory (see my AV column in the December-1999 Analog), a theory that cleverly avoids the point-like particles that make singularities. However, superstring theory is still in the development phase, and has not yet reached the point where it can be confronted by measurements or make testable experimental predictions.
The revision of general relativity theory that I want to tell you about is the work of a group of dissident physicists led by Hüseyn Yilmaz of Tufts University. They claim that a slight modification of the orthodox GR formalism cures the problems described above and offers other mathematical advantages. The Yilmaz version of general relativity modifies Einstein's equations by introducing the assumption that gravitation, like all other energy fields, produces space curvature. Yilmaz implements this by adds a gravitationally produced "stress-energy tensor" to Einstein's equations. The resulting variant of general relativity conserves energy locally and has no singularities. 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 can be shown to be a "gauge theory" (very similar to electromagnetism), a characteristic that makes it more mathematically tractable and easier to obtain multi-body solutions.
When the gravitational fields are relatively weak, the Yilmaz version of general relativity makes predictions that are observationally indistinguishable from Einstein's version. It is only in the limit of strong gravity that the differences between the two theories become apparent in their predictions. This happens when the extra space-time curvature of the gravitational field becomes important. The most dramatic difference is that the Yilmaz version of general relativity is better behaved mathematically and contains no singularities or event horizons. In particular, the Yilmaz theory predicts that there are no black holes. A massive star may collapse to a state more dense than a neutron star, but it never reaches the pathological black hole state of a time-frozen event horizon cloaking a singularity.
At first glance, this prediction would appear to be fatal to Yilmaz relativity. The headlines from recent astronomical observations, particularly those with the new x-ray and gamma ray telescopes, are said to have confirmed the existence of black holes. However, careful examination shows that the new data confirms the existence of collapsed stars that have extremely hot accretion disks and are too massive to be neutron stars. That observation is compatible with Yilmaz relativity. There has never been an indication of actual event horizon. In fact, up to now there have been no astronomical observation that would falsify the Yilmaz version of general relativity.
There is, however, the possibility of observational tests. When a massive star uses up its nuclear fuel and begins to cool, it goes into a catastrophic collapse called a supernova. 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. For more massive stars the nuclear forces are insufficient to overcome gravitation, and the star continues to collapse to something much smaller and denser than a neutron star (call it a "black hole candidate"). The Yilmaz version of general relativity predicts a larger maximum mass for neutron stars than does orthodox GR. Thus, observation of a very massive neutron star would tend to support the Yilmaz theory. In this context it is interesting that recent fast X-ray observations (see my AV column in the November-1998 Analog) 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. There are similar suggestive data from the spectral shapes of X-rays from neutron stars.
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.
The Yilmaz theory is not widely accepted among general relativity theorists. Several critics have published detailed criticisms of the new formalism and its interpretation, and a heated debate has developed in the literature between the Yilmaz group and its critics (see the references).
It is also worth noting that many theorists, the most prominent example being Steven Hawking, have established their reputations based on theoretical calculations that involve black holes. Much of the recent progress in string theory has come by realizing that there is a duality between strings and black holes. What are the implications for theoretical physics in general and string theory in particular, if it were shown that black holes are not real objects, but only artifacts of an unfortunate omission by Einstein in the formulation of general relativity? An unbiased observer can only say that it is a very interesting controversy that must ultimately be resolved by careful calculations combined with observational tests.
The controversy also raises a question that should be of interest to the SF community. Do black holes exist? Or are they only the products of an inadequate theory? The plot lines of many works of hard science fiction, indeed many that have appeared in this magazine, depend on the existence of black holes and on the interesting violence that they do to space-time. Perhaps gravity near collapsed stars is much different than we had imagined. Perhaps there are new effects that become apparent only through application of the Yilmaz version of general relativity. Perhaps there is material for a whole new generation of hard SF here.
The slashdot effect is destroying the internet, sucking helpless webpages into a black hole!
His article...Our Millimeter-Size Universe is pretty interesting.
"Superstring theory suggests that gravity is weak because its extra-dimensional loops are a millimeter in diameter."
If /.'d go here
http://www.analogsf.com/0004/av0004.html
itbwtcl
That's what I miss most about TNG. A lot of TNG episodes were more like the old school sci-fi. Y'know, taking just one idea and working with it. Now with Voyager, it's the technobabble "particle of the week" crap. We need more TNG style writers.
Very few episodes relied on black holes - I can't even think of one TNG off hand.
Most concerned some type of space anomaly - weird entities, vortices, conduits, wormholes, supernovas. Like the big giant dark face that looked like the face of a racoon and wanted to kill only 1/3 of the crew. Spooky and with absolutely know quantum/relativity explanation either!
b) Produce an alternate theory to evolution which suggests certain parts of the Biblical story.
I'm no Chrisian, but I'll say this anyway; I took Sociology way back in high school and one of the most important (to me) concepts I got out of it was that people in our society (American, at least) feel that everything (people, object, etc.) has to have a purpose/use. Anything that doesn't would be considered useless or should be removed. How this relates to Christianity is that Christians are afraid that all their devotion are for naught when something dispels the "truth" found within their beliefs. But, when that something is "made compatible" with the beliefs of Christianity, then Christians still serve a purpose/use within society.
I personally dislike this belief that people/objects/etc. *must* serve some purpose because of how some would use this to justify the elimination of whole groups of people that they dislike or see as "useless".
*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.
It's a bit more difficult if you try drawing a three by three grid of grids and say that they stack up in dimensions 3 and 4, although deciding if you've won yet gets a bit difficult.
I've attempted a 6D game, but I just got a headache.
I've also seen a 4D Rubiks cube at superliminal
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.
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'm sure this is the case for many scientists, as it is for many people. But I don't think this is necessarily the case.
Thomas Kuhn famously postulated that science proceeds by paradigm shifts in which, roughly, a bright young spark comes up with some revolutionary new theory that completely rewrites the old theory, and has to fight against the grand old duchesses/dukes of science until spectacularly vindicated.
Then that theory develops holes and is patched until the next brilliant postgrad, who is then opposed as vehemently by the developers/advocates of the old theory.
I can't give you many arguments against the theory as a whole (aside from my first year philsophy lecturer's statement "Kuhn wasn't trained in philosophy" which clearly says it all and probably argues for a paradigmatic view of philsophy) but point out that many scientists vehemently deny this.
There was one anecdote (please someone tell me the author) which pointed out that although, socially, scientists have as rigid a pecking order as anyone else, when holding a seminar, or discussing a theory, the freshest newcomer has as much a right to an answer (no matter if the question displays ignorance of undergrad material) than the speakers own collegues.
Certainly, I personally deplore the attitude of many people who have taught me science towards the history of their discipline ("What an ignorant lot of twits, we understand it all now"), and sincerely hope that isn't the case everywhere.
An appreciation of the difficult of postulating a scientific theory would help solve the problem you raise, where a 'wrong' answer causes loss of status. That shouldn't be the case.
> Science, when practiced in good faith, however, is immune from such arguments ...
Did anyone else catch the irony in thisCharles Misner is one of the three authors (with John Wheeler and Kip Thorne) of Gravitation, the standard reference work on GR.
Anyone in favor of a stationary Solar System over our current, orbiting configuration, please raise your hand.
If this is right, it means that there are probably only 4 dimensions to spacetime, not 26 or even 10.
So when I say "black hole" to children born after 2001, it's going to sound like my grandfather saying "luminiferous aether" did 100 years ago. On the other hand, it was bound to happen. The name "'polka' dots" was cashing in on a polka (dance) craze. "'Radio' flyer" wagons had nothing to do with radio. "Internet ready" is probably today's equivalent. Or "i-", "e-" or "cyber-" anything.
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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.
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If code was hard to write, it should be hard to read
I can see how the reduction to a gauge style theory clears up a lot of problems, since it allows a Feynman style cancelation of infinities, which in turn makes it *much* more QM compatible in and of itself. But since the final collapse would still be halted by the strong force (or not), I don't see how this would cause the mass threshold to increase to infinity?
Mind you, if it *does* do so, it explains the 'flat space' findings quite nicely - Space as a whole would be flat because space as a whole has no other options than to be flat.
All right - someone with a degree in this explain it - grin
Pug
This has been a test of the Slashdot Broadcast Network . . .
An Invisible Entity of Vast Power whose existence must be taken on faith alone: Liberal Media
So, if I read the article right, this new theory doesn't allow for singularities at all.
I've never really bought into the Big Bang (in fact, Hawkings himself states in A Brief Illustrated History of Time (I don't have my copy handy or I'd give you the ed., page, and an exact quote) that he doesn't even believe it himself anymore.
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.
If you can read this, then I forgot to check "Post Anonymously".
See this aarticle for a refutation of Misner's flawed work. They point out that the serious problems that Misner attributes to Yilmaz theory actually applies to GR, not Yilmaz theory!
the growth in cynicism and rebellion has not been without cause
The biggest problem is that the primary prediction of this new GR theory is wrong. Black holes(aka objects with event horizons) do exist. I am referring to an article in the May 1999 issue of Scientific American titled Unmasking Black Holes.
They use a rather ingenious method to determine whether an object called a quiescent x-ray transient is a neutron star or a black hole. These are objects in binary systems. Basically an object with the same orbital period should accrete matter at the same rate. As matter falls towards a black hole or neutron star it will heat up and release energy through friction with other matter falling towards the object. The more matter the more energy will be released, the less matter the less energy that will be released. The difference occurs when the matter reaches the surface. With a neutron star the matter impacts on the surface of the neutron star and releases energy. A black hole on the other hand should release no energy on impact. So, a black hole should be dimmer than a neurtron star with the same orbital period since it doesn't emit energy due to the impact of matter. Observations have shown that objects with >3 solar masses (black hole candidates) are less luminous than objects with 3 solar masses (neutron stars). Basically, only an object with an event horizon can account for this.
This article is not on their web site. I got it from the dead tree version.
Dastardly
I've submitted at least two references to articles in Analog and/or it's sister publication Asimov's, both of which were far more relevant to /. readers (IP-related), and they were rejected without comment. Slow day maybe ?
If only we could say that of the movie.....
MrCreosote Meow!Thump!Meow!Thump!Meow!Thump! "You're right! There isn't enough room to swing a cat in here!"
- 10 people would post articles consisting entirely of random keyboard pounding ("I can't see!")
- 30 people would talk at length about what life without a head is like.
- 5 serious karma whores would be seriously karma whoring.
- 2 or more would post First post!
- Everyone else will touch their head once and realize that they're either not qualified to answer or the whole headless thing doesn't apply to them.
Wait until that frozen burrito's at least a little thawed before you bite into it, hook, line, and sinker, ok sugar?If you're interested in John Cramer's stuff, or physics in general, etc, check out Schrodinger's Kittens by John Gribbin (I think). It's a very good book that gives an overview of Cramer's Transactional Interpretation of quantum mechanics. You can find the detailed stuff on his site as well, which I don't remember off the top of my head, and lost my bookmark for anyway.