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Einstein's Theory Improved?
skaet writes to tell us that A Chinese astronomer from the University of St Andrews claims to have fine-tuned Einstein's theory of gravity. Dr Hong Sheng Zhao has created a 'simple' theory which could "solve a dark mystery that has baffled astrophysicists for three-quarters of a century." This new law seeks to discover whether Einstein's theory was correct and if dark matter actually exists.
Even if that is the worst graphic accompanying a well-written, intelligent article I've seen in my lifetime.
Ex nihilo nihil fit.
Would people please stop using the word "Law" when referring to scientific theories. It confuses the creationists.
I'm sure that there are lots of people that are far more clued up on this than I am that can find holes in what I am about to say but I always felt like dark matter was a bit of a fudge because we don't understand what is happening.
My problem with dark matter is that it's almost as difficult to believe in as God. The only real proof we have is that the universe doesn't appear to move correctly without it. If that's as good as we can do then we might as well say God (or the FSM) is holding the universe together. To my mind it is a big leap from "the universe isn't moving as we expect" to "90% of the universe is made of something we can't see". Surely if the universe was full of this stuff we would be able to detect it because it would block radiation from distant galaxies - or is dark matter conveniently transparent?
I used to have a better sig but it broke.
How exactly would the law itself discover anything? Wouldn't that have to be a hypothesis first that would have to be tested experimentally before it becomes a law?
It's not dark matter. It's light.
If you check the equations, you'll find that light from a star causes its gravitational field to fall off as 1/r, whereas its mass causes it to fall off as 1/r^2. This is an old equation, originally derived for the gravitational field of a candle.
Needless to say, this effect is only present within the "sphere" of radius (speed of light)x(age of star), but of course for most stars, this is enormous. Galaxy spanning in fact.
This is all relatively offtopic by the way, but given the controversy surrounding dark matter, and the dubious qualities of "landscape theories" lately, I thought I'd throw this one into the mix as well.
I wonder if this is what the guys have come up with actually.
May the Maths Be with you!
Won't it be ready until April? Stranger things have happened.
http://michaelsmith.id.au
What a clear and well-written article. And what a pleasant, unassuming statement from Dr Zhao:
"A non-Newtonian gravity theory is now fully specified on all scales by a smooth continuous function. It is ready for fellow scientists to falsify. It is time to keep an open mind for new fields predicted in our formula while we continue our search for Dark Matter particles."
Even if the theory turns out not to stand up, words like this take us back to what makes science interesting and important. That "falsify" is worlds away from the publicity hounds and egomaniacs who so often represent science to the lay reader.
Las qué passoun
tournoun pas maï
Name something that doesn't!
My problem with dark matter is that it's almost as difficult to believe in as God. The only real proof we have is that the universe doesn't appear to move correctly without it..... or is dark matter conveniently transparent
I have to disagree with that, I have no problem believing in the existance of dark matter. In fact I don't have to 'believe' in the existence of dark matter at all, I found some between my toes this morning and it was most certainly not transparent.
Only to idiots, are orders laws.
-- Henning von Tresckow
Although it is not the theory that has been improved, it is the model. It takes a simple function to interpolate between the dark matter area (which is non Newtonian - Modified Newtonian Dynamics or MOND) and the Newtonian area, where baryonic matter seems to reign. Despite a simple continuation function for the two areas, the authors find a nice agreement with rotation curves of galaxies including our own, and some external ones. The theory which has been used is the TeVeS (Tensor Vector Scalar) theory by Bekenstein. The scalar part of the theory could explain the dark matter behaviour.
E=mc^2
Try looking into ways of calculating coefficient of drag
http://michaelsmith.id.au
Unfortunately, like Cambridge, St. Andrews has suffered from negative publicity as a result of its taking occasional pupils from failing schools and admitting them with A level scores which would not normally allow a student to be admitted. But at least it meant that some of the Windsors got access to higher education, so perhaps the policy is defensible.
Anyway, I'm very pleased that the astrophysics tradition is continuing. But I'm still left with a question: Why are the nicest British Universities (Cambridge, Durham, St Andrews) in such bloody cold places?
Pining for the fjords
I am not an astronomer. I just tend to apply logic to everything I collide with.
And when I can't collide or interact with it, it kinda ruffles me the wrong way. What kinda magical stuff is this supposed to be. Doesn't interact, doesn't shine, doesn't emit, doesn't absorb, all it does is offer some convenient gravity to explain a few things that don't make sense otherwise.
It kinda reminds me how about 500 years ago astronomers came up with double and triple rotations of planets around an imaginary point to explain why the planets move the way they move since they believed the Earth and not the sun is the center of our system. And if they rotated around earth, they had to jump through a few hoops to explain that odd orbits they showed. Instead of abandoning the system that didn't work and accept one that does, they religiously clinged to it and tried to explain what could not be explained.
Maybe we're at that point again?
Maybe, just maybe, it's not dark matter but some of our "laws" are simply wrong. Or, if not wrong, they maybe don't extrapolate well into the larger scale, what works and makes sense in the (comparably) small scale of our solar system doesn't make sense and doesn't work on a galactic scale.
I do hope this is a step into the right direction. Science is all about not setting stuff in stone. Everything has to be questioned, everything has to be tested, even the most holy scriptures from the most revered astronomers of all times should be ripped if they showed an error.
If not, science is no better than religion.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
I've heared once that the original hebrew text reads "Thou shalt not murder." If that's true, the contradiction is easy to resolve: Just define that killing ordered by god is no murder.
My understanding was similar but different. I had heard that the original ancient language of the bible did not have a rich engouh vocabulary to distingiuish between kill (e.g. an enemy) and murder (e.g. one in your own society), but the next most recent translation of the bible used the word "murder", not "kill".
The point is, when Moses was taking his tribe around the desert with their new commandments, they were to preserve their own society (which is what the 10 commandments promote), but if they had to kill competing tribes to survive, they could do so because it would be *killing*, not *murder*. Any society that condones unbridled murder within itself will quickly commit suicide.
The link at the bottom of the page labelled "About PPARC" obviously goes too close to a singularity and ends up in a parallel universe with a quantum difference of this address is a 404 page. They've got me convinced.
It was Kepler who realised that ellipses could be the correct model for orbits, and even there, to try and keep the Church happy, he tried to fit the major and minor axes into the shapes of the "Platonic solids".
History suggests that the example you are quoting is the opposite of what you want to show. It is better to let scientists come up with initially ad hoc explanations because they lead to the truth. Making initial unscientific assumptions and treating them as dogma suppresses and delays progress. Scientists are ambitious and a good way to become important is to replace someone else's theory - so scientists can be relied on to do that. For every established Dark Matter theorist there are probably several PhD students who would love to annihilate Dark Matter.
The line of argument in the parent annoys me because it tries to suggest that scientists left to themselves will produce ridiculous non-explanatory theories and then cling to them forever. It's the anti-scientific agenda of the Creationists who want to discredit science. Creationists and their like want to confuse the public as to the explanatory status of different scientific theories so they can claim their snake oil is on an explanatory par with plate tectonics, quantum electrodynamics or evolutionary biology.
Pining for the fjords
His identical twin brother won't have returned from a journey around the universe at 0.99c until April
init 11 - for when you need that edge.
Tell me about it ...
:p
Every year I've been in Cambridge (since 1996) the winters have been bitterly cold, whilst not having the benefit of much snow. It's the nasty artic winds sweeping down off the North Sea, over the flat land straight into Cambridge. Grr!
Still, it cools our heads, allowing our brains to operate faster
(if only)
(1) Jobs where if you goof up, some money goes down the drain, or you're embarrassed or, somebody gets hurt or dies. You know, like being a doctor or lawyer or engineer.
(2) Jobs where it doesnt matter one whit if you're wrong. Jobs like theoretical physicist in a field where there isnt the slightest possibility of carrying out an experiment. Such as dabbling in the theory of gravity.
Like an idiot, I'm in category #1. What a dope.
E = mc^2 and sometimes Y.
You see? You see? Your stupid minds! Stupid! Stupid!
... just last week or so, we were told there was *no question* that it exits; we're just studying it's properties now. No question *at all*: commence ridicule of any who disagree.
Just who are we supposed to ridicule now? Would someone please give me my nerd marching orders?
What great timing the bbc has, only last week Horizon aired a documentary on the search to find, or disprove the need for dark matter. A synopsis is here : - http://www.bbc.co.uk/sn/tvradio/programmes/horizon /missing.shtml.
What was good about this one in particular was that the scientists actually seemed to be open minded and not clinging to their theories with an immature pride. Even the 'defenders' of dark matter were open and interested by the idea of modifying the laws of gravity.
What made me laugh is that one Professor has been in the bottom of the deepest mine in Europe for 16 years searching for neutrinos, and has found nothing.
If this were really happening, what would you think?
Or am I the only one who is almost completely jaded to "Yet another theory this year that challenges our understanding of the universe".
Our we all jehovahs Whitnesses or what?
Oh wait, I guess every project needs funding. More importantly every scientist needs funding and since global warming is taboo via near Presidential verdict, lets go after dark matter and the E-man himself.
Almost easier if you go after Darwin, oh except thats not physics and that is also taboo due to political unrest given this semi-new intelligent design crap. Hmm. Better to go after physics itself, chruch goind fundamentalist creationsts dont care about that, Presidents dont care, its a clean cut case of fundage.
Excuse me whilst I be jaded to myself for a moment..... Oh, by the way, fuck everyone who challenges Einstien and the usefull parts of Darwin. Give it up for like a few years.
Damnit, bring on the new!
Its currently like an alternate reality game show.
At least Jehovahs Whitnesess have the forsight to delay all scientific information by at least a year (or a decade).
Sorry, I know I dont have to troll on this and I did not have the option to not RTFA. I am not complaining about the coverage. I think I am bitching about everything except the coverage.
Do we really have nothing new but Mars and the newest explanation of Dark Matter? If so then let us admit it.
Yes I am a bitchy mood.
I think you underestimate just how much I just dont care.
PPARC still posts the scientists e-mail addresses in tfa? I can think of many spam e-mails that contain 'dark matter' but not of the kind they're looking for!
Time is an illusion. Lunchtime doubly so. - Douglas Adams
The statement that "science is/isn't better than religion" is not scientific, it's rather religious.
Yesterday was the time to do it right. Are we having a REVOLUTION yet?
The GULLIVER supplement for GURPS by T.Bone has a simplified method to calculate terminal velocity. I haven't read it in a couple of years, but AFAIR it mainly covers TV for people and creatures. Hope this helps.
Excuse me, wtf r u doin?
http://arxiv.org/abs/astro-ph/0512425 The phenomena customly called Dark Matter or Modified Newtonian Dynamics (MOND) have been argued by Bekenstein (2004) to be the consequences of a covariant scalar field, controlled by a free function (related to the MOND interpolating function) in its Lagrangian density. In the context of this relativistic MOND theory (TeVeS), we examine critically the interpolating function in the transition zone between weak and strong gravity. Bekenstein's toy model produces too gradually varying functions and fits rotation curves less well than the standard MOND interpolating function. However, the latter varies too sharply and implies an implausible external field effect (EFE). These constraints on opposite sides have not yet excluded TeVeS, but made the zone of acceptable interpolating functions narrower. An acceptable "toy" Lagrangian density function with simple analytical properties is singled out for future studies of TeVeS in galaxies. We also suggest how to extend the model to solar system dynamics and cosmology, and compare with strong lensing data (see also astro-ph/0509590).
They have created a formula that allows gravity to change continuously over various distance scales and, most importantly, fits the data for observations of galaxies...It is time to keep an open mind...
There is not much in this article that gives us a clue as to what they are referring to. But I guess we have to wait for their Edinburgh presentation in April.
He who knows best knows how little he knows. - Thomas Jefferson
"The new formula will be presented to an international workshop at Edinburgh's Royal Observatory in April, which will be given the opportunity to test and debate the reworked theory. Dr Zhao and Dr Famaey will demonstrate their new formula to an audience of Dark Matter and gravity experts from ten different countries."
No preassure. *phew*
SIG: TAKE OFF EVERY 'CAPTAIN'!!
They have created a formula that allows gravity to change continuously over various distance scales and, most importantly, fits the data for observations of galaxies. To fit galaxy data equally well in the rival Dark Matter paradigm would be as challenging as balancing a ball on a needle, which motivated the two astronomers to look at an alternative gravity idea.
:)
Difficult? Sounds like they needed to find the slope between two points to me
The map is not the territory. It doesn't matter if the theory invokes a state of matter which cannot be directly interacted with: if it fits the existing data and makes testable predictions regarding new data, then it's valid. Occam's razor (which is to do with removing theories found to be practically indistinguishable from other, simpler theories) doesn't come into it at this stage because the various theories make different predictions.
No kidding!!! What do you say at this point?
My intuition says this is not going to hold up. Firstly, this seems to be an ad hoc theory to explain the fact that galaxies rotate too quickly. There's nothing wrong in ad hoc theories as such, but when it comes to theories like Newton's and Einstein's theories for gravity, they are so well tested that I would expect any amendment to be based on something more substantial.
;-)
Secondly, Newton's formula for gravity around a point mass (on which Einstein's theory is based) seems to fit very well with one's intuition: think of gravity as a sort of 'substance' that 'emanates' out from the point mass; the amount of 'substance' stays constant as it propagates outward, but the area of the resulting sphere of the substance grow as the square of the distance, so the density of the substance falls off as the inverse square of the radius. It makes sense to, at least; it seems natural. Now, in this intuition, if the force of gravity didn't fall as fast as 1/r^2, some 'substance' must have been added along the way - where does it come from?
This is of course only intuition, but that can be said of both general relativity and quantum mechanics too (in their own circumscribed way). Take Heisenberg's uncertainty principle, the intuition here is that all particles are waves, and to measure the properties of one wave/particle, you have to hit it with another. Someone has calculated how good a resuolution you can get from measuring something with waves interactions like that, and from that came Heisenberg's principle; very intuitive, I think.
This amendment to gravitation doesn't seem to have that element of intuition, simply, but perhaps it wasn't explained very well in the article.
Apart from that - dark matter as an explanation isn't very satisfying. It seems to be too much of a big, black box; I can't think that that will be all there is to be said or discovered about 90% of the whole universe, I fully expect that there will be at least 10 times as much detail to discover in physics as we already know. And I'm going to be right there when it happens
I also don't like dark matter/energy theories very much (although I do like the idea that there is more out there that we don't know about). Nor do I like string theories. I think the whole of physics is somehow run amok. A few things do appeal to me however, probably because of my feeling that ultimately it all boils down to a computational algorithm. I think that some aspects of quantum theory fit like the "Bekenstein bound", and that this relates to gravity over the large scale.
For example, when it comes to gravity, we might think of space itself as a substance, not a material substance, but a substance of which all "material" things are made. A volume of this "space" substance then has various "densities" within it, giving cause to gravity, and causing light to bend, in much the same way as light bending through glass of varying density.
Now, when it comes to the galaxy problem mentioned in the article, we might see a galaxy as a "condensation" of hydrogen at the boundary of the region of high and low pressure of the space substance "density". In this model we are viewing a galaxy much like a hurricane forms. A hurricane is a self sustaining structure within a volume of air giving rise to the formation of clouds, and rain. A galaxy is a formation of condensing hydrogen at the boundary of a high and low density of space (seem to be repeating myself). Due to this model, gravity does not vary directly from the center of the volume of the galaxy, but follows the general structure of the galaxy itself.
So what is this space substance of which all things are made? Does it matter (pun intended)? If we see this space substance as a mathematically "continuous" substrate that can manifest all objects, then what is it that gives rise to "size"? If quantum mechanics and the Bekenstein bound are correct, then the "continuous" substrate of space is actually punctuated with perfect sinusoidal waves. These waves, through self interaction and superposition give rise to location, eg. points in space where some things are, and some things aren't. The chaos of this wavy interaction ends up dividing space into a "resolution", much like your computer screen has a resolution. All material objects are then constructed of these wavy interactions that are happening at the Plank resolution. However, the Plank resolution should vary directly as the "density" of space, eg, the resolution of space should be high near a massive object, and low where there is no mass.
Do I believe any of this? No, not neccessarily, as Mony Python says, "it's just a model." But I really like theories that are simpler, instead of more complex.
Although I share your skepticism about dark matter, I couldn't help thinking about the neutrino, a "hidden" particle that filled another gap in physics. It took 25 years for physicists to finally detect the neutrino.
Mea navis aericumbens anguillis abundat
They are both quotations from the same book.
It's better to be the foot on the boot than the face on the pavement. ~~ tkx Kadin2048
Classical physics, which includes both Newtonian and Einsteinian mechanics, is mostly descriptive math engineering. Math does not explain physics; on the contrary, it's the physics that explains the math. For examples, they do not explain why things fall or why bodies in motion remain in motion. The beef of a physical theory is the mechanism that is responsible for the observation. Where is the beef of relativity? Until someone comes up with the beef, neither theory can claim to be physical theories, in my opinion. They're just math tricks with no real physics. The best way to improve Einstein's and Newton's theories is to unravel or model the actual physics behind the math. Until then, it's not much better than ptolemaic epicycles.
PS. I already heard the usual ripost by relativists to the effect that science is not about the why of phenomena but the how. IMO, that's just a lame copout to excuse their ignorance and mental laziness. I already know that bodies fall and move; I want to know why they do it, if you don't mind. And please Brian Greene, stop preaching the nonsense about gravity being caused by the curvature of spacetime. Nothing moves in spacetime. ahahaha...
That, ladies and germs, is science. That's how you tell the crackpots from the professionals. That's what separates the good guys from the Time Cube-style guys.
I wonder if he'll accept my invitation to dinner. We'll have cake.
From the header...
This new law seeks to discover whether Einstein's theory was correct
So now we have a sudden new law that seeks to disprove an established theory? Yet this law has not even been tested? Someone has their terms mixed up. There are very few laws in science and they include very measurable and reproducible things like gases, thermodynamics, charge, resistance, gravity, and newtonian motion (I may have missed a few). Then suddenly we're into theories because our ability to measure either interferes with the results or we can only observe our results indirectly.
I keep an open mind but this guy pegged the needle on the crank-o-meter calling it (from TFA) "a new law for gravity" from day 1.
Seven puppies were harmed during the making of this post.
It really pisses me off the leeway we give theoretical physicists. If an engineer screws up on a bridge, or if a doctor screws up on a patient, people know, and they demand accountability. If astrophysicists fail to properly apply an equation for 100 years, or miss something simple for 75 years, "hey, that's science, it's tough man, cut us some slack". How many times have they changed opinions on whether the universe is expanding or contracting now? And just so you don't misunderstand, it's absolutely okay to make mistakes -- as long as they're new! Each time scientists err in a theory and "change their collective mind" about something, it should come with a fundamental re-evaluation of what practices led to the error, and what kind of evidence counts as proof. If they did that, you wouldn't see them switch opinions about some matter every third year, or, even better, admit they don't know.
Rank my idea: http://www.sinceslicedbread.com/node/531
This is not an improvement to Einstein's theory of gravity. It is, however, an improvement to Milgrom's Modified Newtonian Dynamics (MOND): MOND is merely an empirical correction to Newtonian gravity, so this is an improved 'empirical' gravity (well, it's got to survive a few more tests before we know if it's an improvement to MOND).
One big difference between Newton's theory of gravity and Einstein's theory of gravity is that Newton's theory says what gravity does (ie. it gives us the magnitude and direction of the force of gravity between two objects) whereas Einstein's theory says that and how as well (i.e. mass curves space-time). Einstein's theory improves on Newton's in that it is more accurate and actually provides insight (testable) into how gravity actually works.
It is likely that Einstein's theory will be improved upon at some time, and be replaced by a more enlightening theory (quantum gravity? string theory?), but for now it is the best theory of gravity we've got....
#include "cunning_plan.h"
Fine-tuning sounds great for an automobile, but in physics if a theory is fine-tuned it means that it is unnatural or unpredictive.
If you look at a reasonable plot of data, you can probably fit a curve through it. But where did that curve come from? If your theory admits any curve, then 'fine-tuning' the curve to fit the data is not much of an achievement. And if you 'modify the equations of gravity' so that rotation curves of galaxies match observation, while abandoning any fixed theorical principle for guidance, then you haven't done much. Unless of course you come up with a new theoretical principle---which is what Einstein did when he abandonded Newton's framework.
Gravity's interaction is _derived_ from general relativity. If you play around with the derived equations, you lose hope of understanding where they came from, and we're back with Newton. If you get rid of general relativity (which approximates to Newtonian theory in most reasonable every-day limits), then you also have a whole lot of new problems.
Modified Newtonian Gravity (MOND) theory has been around a long time. Dr Zhao's realisation is new, but not the idea or framework. As such, it solves the 'dark matter problem' while complicating many other things.
Evidence for the 'dark matter problem' comes from big bang nucleosynthesis, galaxy surveys, rotation curves, galaxy cluser dynamics observations, weak and strong gravitational lensing, the cosmic microwave background, and large scale structure simulations. Many of these problems are inter-related. MOND theories usually address roation curves while spoiling any hope of explaining all the rest.
I think you've hit the nail on the head. Unfortunately, with the omnipresent media that we have nowadays, they need to find little tidbits, regardless of their accuracy or proof, that can fill up a quiet hour on their 24hour news shows.
On an aside, I read somewhere (can't find it now though) that the news shows are starting to have to come up with a new phrase for breaking news because it was constanly on the screen regardless of how long the news had been broken.
I know what murder is, I just wondered what people actually thought of it themselves, rather than the definition of it, which aren't always the same. You yourself seem to think that killing an enemy soldier is murder, but also agree that murder is "The unlawful killing of one human by another, especially with premeditated malice". The whole idea of a soldier being an enemy soldier is that you are at war, and therefore are legally allowed to kill the enemy (unless they surrender)
Also yeah if you dont want to get shot at, then not joining the Army is a good idea, but that does seem a bit selfish. I've never quite believed that we went into Iraq for valid reasons, but if lives/nations are saved through it, then it is a valid use of the army's resources (which would include soldiers' lives.. they presumably knew what they were signing up for.. but most lives lost that we see on the news from Iraq seem needless and petty, and not even a result of proper combat..)
which is totally what she said
"If something doesn't work first time, invent something imaginary"
This is not the first time in which an existing theory has had a part added (a fudge factor if you will...) to explain an anomalous phenomenon.
Such example include,
1. God
2. The aether
3. The cosmological constant
Each of these ideas have been used at some point to ensure that an existing theory (or foundationless preconceptions) coincide nicely with observation. In each case, they have been refuted at some point in the future.
The idea of modifying the rate of gravitational fall off with distance is not a new idea - back in the 1800s, Airy (If I remember correctly) discovered that if instead of gravity obeying an inverse square relationship, it obeyed an inverse relationship to a different power, the predicted orbit of mercury would fit the observed data. If this was proposed however, there would have been a lesser incentive to look for the more accurate theory that General Relativity provides.
I can't help but think that very rarely does true progress come from simple modifications to existing theory. When theory does not match observation, it is often a new idea entirely that is needed to resolve the problem. A modification to an otherwise elegant idea usually obscures the truth.
If this new theory really does provide highly accurate results, we should ask why and look for the underlying cause of gravity falling off faster than expected, rather be complacent with the introduction of a new constant.
Nothing sucks like a Vax, nothing blows like a PowerMac G4
First off, I want to say a few words about dark matter. I think it's kind of irritating when people rant on about how dark matter is ad hoc fudging, etc. etc. Well, "fiddling around with the laws of gravity" isn't any better on that account. The fact of the matter is that all of theoretical physics is creating new models that fit our observations, and both dark matter and MOND fall into that category. The very existence of MOND as a theory shows that it is not easy to distinguish "matter that primarily interacts gravitationally" from "modifications to the laws of gravity". Historically, both "unseen matter" and "modifications to gravity" have been valid solutions to anomalous gravitational behavior (in the cases of Neptune's orbit and the perihelion precession of Mercury, respectively).
As it stands, dark matter models can pass many experimental tests, and they're still the way to bet. That being said, MOND is not a bad idea either. It's not as well supported by dark matter, and it has serious problems with galaxy clusters, but it can still account for a surprising amount of data (for a nonrelativistic theory!). The flaw of non-relativistic has been "corrected" by Bekenstein's TeVeS theory (the one that Zhao and Famaey's work is based on).
Unfortunately, TeVeS appears to be rather ad hoc (even compared to dark matter). Z&F's work does not appear to be much better in this regard. In addition, solar system observations appear to place serious constraints on such MOND-like theories, leading to anomalous non-inverse square forces in the outer solar system (and no, it doesn't seem to be of a form that can be attributed to the Pioneer anomaly, though the jury is still out).
The TeVeS/dark matter debate should be definitively resolved by the Planck mission, which will be capable of resolving the third acoustic peak in the the cosmic microwave background radiation power spectrum. TeVeS and dark matter make very different predictions for the structure of this peak. Of course, if TeVeS fails this test, maybe some other MOND-like theory could be put forward (if the entire class of theories hasn't already been ruled out by other means, such as solar system dynamics, by then).
Being completey undereducated I will nevertheless offer my little theory. Most of the unaccounted for gravity is due to frame dragging. The faster an object spins the more it pulls on the space surrounding it and increases its gravitational pull.
So, you're saying it's good to be the king. That's one of the best backhanded compliments I've read in a while. You must keep your standards on the lowest rung lest you fail to allow those on the highest rung in. In America, we are a little more pragmatic. We simply redefine what high standards are similar to the way torture has been redefined. It's not torture unless it causes organ failure or impairs bodily function. How else could we end up with best and brightest in our highest office?
"You'll get nothing, and you'll like it!"
A galaxy is modeled as a stationary axially symmetric pressure-free fluid in general relativity. For the weak gravitational fields under consideration, the field equations and the equations of motion ultimately lead to one linear and one non- linear equation relating the angular velocity to the fluid density. It is shown that the rotation curves for the Milky Way, NGC 3031, NGC 3198 and NGC 7331 are consistent with the mass density distributions of the visible matter concentrated in flattened disks. Thus the need for a massive halo of exotic dark matter is removed."1 0/1052224&tid=160&tid=14 0 7619.pdf
http://science.slashdot.org/article.pl?sid=05/10/
http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0507/05
"... the intrinsically linear Newtonian-based approach used to this point [in the study of the motion of Galactic Bodies] has been inadequate for the description of the galactic dynamics and Einstein's general relativity should be brought into the analysis within the framework of established gravitational theory."
I guess that most Dark Matter proponents haven't yet read this important paper that debunks the need for Dark Matter. Ah, if you get the math wrong you need Dark Matter... if you don't you don't!
The article is NOT well written. It doesn't explain anything other than in vague terms. A cat chewing on a lemon would make more sense.
No, that's not what happens. Laws say what happens, theories say why and/or how it happens. Laws don't try to explain behaviour, they just state it. Hence the laws of thermodynamics are laws, while the theory of relativity is a theory and always will be.
:-)
And the law of gravity? Observations say what happens. Theories say why and/or how it happense. Laws are what we call theories we think will never be falsified, and it's probably a word that should be dropped from any kind of scientific discussion, since we all should have learned by now that even the most basic assumptions and most obvious conclusions drawn from the most irrefutable of observations have a way of requiring revision from time to time, as better observations are made (Newton couldn't look at gravitational motion, and we cannot yet see into the higher folded dimensions of string theory, assuming such in fact exist).
The "laws" of thermodynamics are as theoretical as relativity. Both have been observed, both are mathematically modelled to great precision, both make useful predictions, both are falsifiable, and no one outside of a few religious wackos expects either to be falsified. That doesn't mean they won't be.
Someday we might find conditions in which entropy in a closed system decreases (candidates for something like this include the time leading up to the big bang--if such is found to have existed--and certain theories of the internal workings of black holes, etc.). Not that I or anyone else realistically expects this (but then, who expected the anomalies that would lead to the dark matter/energy vs. non-newtonian gravity debate, either), but the "laws" of thermodynamics are as falsifiable as the theory of relativity and, as it turns out, the "law" of gravity.
Theories do have a habit of becoming "laws" when they are basically considered irrefutable. They shouldn't--we should probably refer to gravity as the theory of gravity, and the laws of thermodynamics as the theories of thermodynamics. It might stop the "big bang theory" and "theory of evolution" rhetorical nonsense we've all been subjected to by communications majors coasting through college with a "C" average only to become network anchors...and help all of us to think clearer. That having been said, I imagine my calls to refer to the laws of thermodynamics as the "theories of thermodynamics" would fall on my old physics professor's deaf ears. Most of us like keeping our language the way it is, no matter how cumbersome or confusing it becomes--but that's a rant for another day.
The Future of Human Evolution: Autonomy
gah
Newton couldn't look at gravitational motion
should read
Newton couldn't look at galactic motion
The Future of Human Evolution: Autonomy
New and improved: Realitivity 2.0!
Now with AJAX!
I read
Ok Anonymous Coward, those papers appear to attempt to refute the Cooperstock and Tieu paper. I wonder how Cooperstock and Tieu have replied to these critisms?
Dark Matter, the magical substance, just seems contrived and, well, magical. The FSM seems to have more reality than Dark Matter... where is the proof?
Why don't the theorists stick to explaining what can actually be observed and measured, instead of making up stuff in order to prop up theories that have more likely found their limits. I can just feel which way Occam's Razor is eventually going to cut on this one.
Unfortunately for you, the universe doesn't care a fig for your feelings. Cardinal Bellarmine could "just feel" which way Occam's Razor was going to cut on the whole heliocentric thing, but that didn't make a damn bit of difference to how best to describe the universe in the most parsimonious way.
This is what differentiates science from religion: becoming a scientist involves training in a kind of epistemological ruthlessness, so that enough of us to get the edge on our feelings often enough that we learn something now and then about how the universe actually is, rather than how we'd like it to be.
The article contains one of the nicest comments I've seen on the whole galactic-dynamics, large-scale cosmology situation:
"Dark Matter particles come naturally from physics, with beautiful symmetries and explain cosmology beautifully; they tend to be everywhere. The real mystery is how to keep them away from some corners of the universe. Also Dark Matter comes hand- in-hand with Dark Energy. It would be more beautiful if there were one simple answer to all these mysteries"
This is the essential point: the large family of unrelated dark matter particles required to explain different aspects of large-scale dynamics without messing up anything else is just not very elegant or pretty. That doesn't mean it is wrong, but when we start multiplying entities in the way that is required to use dark matter to explain dynamics on different scales it gives us pause. When we further have to fine-tune the properties of the different, unrelated particles to ensure they don't have any effect in places where they are not needed...well, with enough free parameters you can fit an elephant.
As an ad hoc rule for theory selection, we would like our theories to have as few free parameters as possible, and when the number of free parameters starts getting close to the number of phenomena we are trying to explain we start to get queazy. Newtonian gravity is beautiful because with one free parameter (G) we get to explain the motion of the wandering stars, tides, and falling bodies. General relativity has at least one more free parameter--the cosmological constant, which is not an "addition" to the theory but a perfectly ordinary constant of integration that has a formal mathematical place in the theory even if it happens to have a value of zero. But GR explains a lot of stuff that Newton does not, so it makes people happy too.
The problem with non-dark-matter explanations of large scale dynamics has been that they have so far had a large and basically arbitrary number of free parameters, and beyond that they have had some nasty mathematical properties. So if this really is a "simple" non-Newtonian theory of gravity it would be quite exciting. This, of course, is why theorists need to keep freebasing new ideas: it can take decades of sifting through speculation and failure before someone finds a viable way forward.
Blasphemy is a human right. Blasphemophobia kills.
The simplest version I've seen is found at wikipedia:
http://en.wikipedia.org/wiki/Terminal_velocity
Vt = Sqrt(2mg/CdA) where:
m & g are the mass of the object & gravitational acceleration
C is the drag coefficient
d is density of the fluid (I'm assuming air)
A is the cross-sectional area of the object
You can't get much simpler than that because C does vary.
For those that are interested in this, Jacob Bekenstein (the author of the first relativistic MOND paper ~2 years ago) has a paper on the preprint server today about the possible measurable effects of MOND in the solar system.
I couldn't tell if you were experimenting with poor-man's cryogenics or looking for the orange sherbet.
> I personally, have a complete dislike for the idea of dark matter. It seems like a stab in the dark, that missed, and was declared right anyway. "Wow, galaxies spin way faster than we think they should. It's almost like there are invisible halos of super heavy matter surrounding all galaxies." Oh, yeah, beyond being completely invisible Dark Matter exists in halos around galaxies. They are really really heavy but the stars don't fall into the halos or the halos into the stars. It's all magically perfect.
'Nuff said.
Sheesh, evil *and* a jerk. -- Jade
You yourself seem to think that killing an enemy soldier is murder, but also agree that murder is "The unlawful killing of one human by another, especially with premeditated malice". The whole idea of a soldier being an enemy soldier is that you are at war, and therefore are legally allowed to kill the enemy (unless they surrender)
Nonsense. Murder is wrong, unless we call it a "war", and makes it okay? No. It is *always* wrong to initiate the use of force against another person. The only time that the use of force is justified is to defend oneself or another against a person who has initiated the use of force.
Downmodding is the refuge of the weak. Don't downmod, make a better argument!
Precisely what I thought when reading it. It reminds me why I respect science and scientists, toiling to provide a shared understanding of our universe. There is an essential aspect of humility to science - submitting your ideas to live or die under the scrutiny of the community. Not that it's always so gracefully exemplified.
The problem is that as a result physicists really, really like very elegant theories when there's no particular reason to believe that the Universe itself has the same bias. Similarly, we like to take theories that work on scales and locations that we know and can easily interact with, and assume that they smoothly apply in the places that we can't get to know quite so easily. It's reasonable even if it isn't logical - we have to go with what we already have. It's a decision born of practicality.
In Cosmology, there's even a phrase for this: we assume homogeneity and isotropy. That is, that there's nothing special about where and when we are, and that the universe is pretty much the same (in physical laws) everywhere. The first time I heard about "dark matter," it was in the context of closure of the Universe. Physicsts really really wanted the universe to have enough mass/energy in order to be "closed," but we simply weren't finding enough matter. There was no reason to believe that the universe is closed (curvature 1.0), but it just seemed more elegant. So, they started to look for the "missing mass."
These are not logical assumptions, they're just assumptions that we have to make in order to get anywhere. Again, there's no reason that the universe will cooperate on this matter.
My own bias is to reject dark matter in favor of a revised theory of gravity, but that's just my own love of elegance - a different gravity feels more elegant than dark matter and dark energy, and in fact would hint at much more interesting cosmologies. But that's just how I am seduced by elegance...
"It is our blasphemy which has made us great, and will sustain us, and which the gods secretly admire in us." - Zelazny
If one keeps looking for presence of something that seemingly should be there but yet doesn't seem to be, perhaps it's time one considers that perhaps a lack of something might be responsible for the same effect? Nature abhors a vacuum and all that.
Hey, it's Tuesday: The day of the Tues! Happy Tuesday to you.
Everything in the Universe sucks: It's the law!
Into which category would you place WWI and WWII, then?
Just a thought.
We all know murder is wrong, I was talking about killing. Which I would also think is wrong, but apparently it's allowed sometimes, like in self defence as you say. Going into Iraq isnt exactly self defence though, unless I guess you count the whole of humanity as 'self', and then defend yourself when you are oppressed. Or if you count defending your interests (in this case oil) as self defence?
which is totally what she said
Does 'justified' mean morally good? I have discovered that a good way to start a flame war is to state that war is always morally wrong, even a justified war. Then, a pile of people who should know better come out of the woodwork to argue that war is a moral thing.
Seems to me that war is a bad thing, always. Sometimes, you've got to choose between a bad thing, and a worse thing. That choice doesn't automatically turn the worse thing into 'evil' and the merely bad thing into 'good'. They both are still bad.
Comments?
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
Genocide isn't bad as long as it's he right kind of genocide, and they are Bad People. I'll keep that in mind next time I want to exterminate an entire population.
"The impossible often has a certain integrity that the merely improbable lacks" - Dirk Gently
I am, having spent 4 years in gravity research and having taught university general relativity.
Then why hide behind "Anonymous Coward"?
Oooo, let's cover up your profound ignorance of the evidence for and against dark matter by calling it "magical". That neatly obviates the necessity for you to muster any scientific arguments against it.
I understand the arguments for Dark Matter and they don't make it sound any less Magical. Besides, it's incumbant upon those (i.e. you) who propose an "Extraordinary Theory" (such as Dark Matter) to provide the extraordinary evidence for it.
The Extraordinary Evidence standard is applicable to Theories of God (really Theologies of God) as well those of Science. Dark Matter may or may not be proven; while it might be falified by someone, as a proponent of it it's up to you to prove that Dark Matter correlates with Reality and to offer the extraordinary evidence of it's existance.
It's not relevant whether or not I like Dark Matter. The evidence just isn't conclusive. Where is the extraordinary evidence for it's existance? Where is a jar of the stuff (so to speak assuming it can be held in a jar in your hand)?
What is interesting about this discussion and the large number of new "theories" to explain the anomolies in galactic motions is that it's the cutting edge of human understanding. Oh, by the way a writing style that borders on insults (e.g. your profound ignorance comment) and ad hominem methods isn't needed and just reflects upon your abilities to argue.
Ahh, I thought this was a reference to the slaughtering of Amalek (1 Samuel 15) where Saul they were ordered to slaughter everything, but Saul left the king alive along with the good animals. Because Saul disobeyed God removed him from kingship, and Samuel rebuked him pretty harshly.
Computers allow humans to make mistakes at the fastest speeds known, with the possible exception of tequila and handguns
In the game of Nomic, the rules of the game include rules for changing the rules. However, there are initially two rulesets, mutable and immutable. An immutable rule must be voted into the mutable class before it can be changed. This is essentially, I think, the same situation we see in the discussion of Laws vs. Theories.
The utility of having a special class of theories we call "Laws" is that they make science more stable, and essentially frame the direction of investigation and new theorizing. What Dr Hong Sheng Zhao and his collabators are doing is essentially calling for the Law of Gravity to be moved into the mutable class.
He who refuses to do arithmetic is doomed to talk nonsense.
'Dark Matter' really describes the problem more than anything. I don't think that when the solution is found anyone will refer to it as 'Dark Matter' any more.
Please sign petition to restore sanity to our banking system!!!
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'Dark Matter' is really a way to describe the problem. When the solution is found I doubt whatever it is it will be described as 'Dark Matter'.
It is different than the study of silly strings, which sop up millions of funding dollars and has produced nothing.
Please sign petition to restore sanity to our banking system!!!
http://financialpetition.org/
I thought this whole mess was cleared up back in 1977.
The Force is an energy field created by all living things. It surrounds us, it penetrates us, it binds the galaxy together.
Why don't the theorists stick to explaining what can actually be observed and measured, instead of making up stuff in order to prop up theories that have more likely found their limits.
Um, yeah, that's what they're doing. We have [b]observed[/b] and [b]measured[/b] things that the existing theory of gravity doesn't explain, so the theorists are trying to develop new theories to explain it. The ultimate goal being to craft a new theory that can make predictions which further [b]observations[/b] and [b]measurements[/b] can either falsify or verify. If the data verifies the predictions, then we have a good theory -- until we make an observation that the theory does not predict.
If you think "making up" dark matter to explain observations within the constraints of Einstein's theory is silly, what would you have thought about "making up" the concept of masses warping space-time to fix problems with Newton's theory?
The enemies of Democracy are
Based on the information in the article, it's not clear what physical principles he's appealling to that would justify adding more parameters to the gravitational model.
I could generate a bicubic mesh from a bunch of random data and claim that I had a "theory" that explained it all. Noone would ever be able to "invalidate" my claim that a polynomial fitting function matched all available data.
But no matter how complicated my polynomials become, my curve-fitting exercise will never reveal that the random data is created by radioactive decay.
It doesn't smell like Physics to me...
Heh, I'm a moron.
The enemies of Democracy are
The original text, in the Torah, is written without vowels. What you were seeing, with vowels, is known as a Chumash - an individual book that is used for daily reading of the Torah's text. The actual scroll(s), known as "A Torah Scroll" in english, is written without any vowels at all and has been that way for thousands of years - google "The Dead Sea Scrolls" for more evidence.
Your assertion that I'm ignorant about Dark Matter is not more than an irrelevant opinion and is an ad hominem attack; as is much of your above posting. I request that you take up a writing style that avoids ad hominem person attacks starting with your very next posting.
Not having a Slashdot account makes it difficult to know if you are the same poster from post to post. At least a Slashdot account let's others know that it's likely the same person posting or responding to a post.
The point about Dark Matter being magic isn't intended to "deride" the hypothesis of dark matter; it is what it is. The hypothesis will stand or fall as people examine it over time and find the beyond doubt conclusive and extraordinary evidence for it or not. Dark Matter makes extraordinary claims and while there is some evidence for it so far there isn't extraordinary evidence for it. Some of the claims just seem magical, unreal and not related to everyday experience; while that characteristic is common in much of physics it's especially true of the Dark Matter hypothesis (and others such as the String Hypothesis).
I didn't ignore your link to what you assert is your list of Dark Matter evidence. It simply wasn't relevant to my posting. The linked posting was well written I might add just so you know that I read and considered it.
By your own statement you assert that "Nobody claims that [Dark Matter] has been 'conclusively' proven"; so how can you attack my request for "extraordinary evidence"? It's not only a reasonable request, it's at the core of the Scientific Method that those who make (or support) the extraordinary claims find the extraordinary evidence and present it.
I make the same requests of those who support or proport the notion that God or the FSM exists. Where is the proof? Where is the reality based extraordinary evidence?
As to the paper "General Relativity Resolves Galactic Rotation Without Exotic Dark Matter", by Cooperstock and Tieu, which suggests that physicists have got their math wrong it's very probably the case; whether or not Cooperstock and Tieu are right with their math is a different question. If you look at the various hypothesis being proposed, Dark Matter, MOND, Strings, M-Branes, etc... they for the most part exist in the world of mathematics (the questions are how and if they correlate with Reality). So it's not a stretch or an insult to question the accuracy of the mathematics involved. In fact that's the basis of the papers that you presented attacking the "Cooperstock and Tieu" papers - that they got their math wrong. So it's common for physicists to assert that the others have got their math wrong. Since we've yet to hear further from Cooperstock and Tieu bowing to these newer papers assertions about their work it's not a dead subject yet - they (or someone else) may still come though with additional adjustments to their hypothesis taking into account any valid critisms. That's the nature of the process of progress in science.
Your statement I mean really, where do you get off telling the entire dark matter community that they "did the math wrong" and were trivially disproved by two guys with a rejected paper that was debunked six times over? is an ad hominem attack against Copperstock and Tieu since you assert that they are simply "two guys" when compared to the "dark matter community". Let's see now, Copperstock is a professor with the University of Victoria's Department of Physics and Astronomy which makes him a little bit more than a run of the mill guy. It also makes him someone who is qualified (by his peers) to assert that the entire dark matter community did their math wrong; and that's exactly what he did in his paper. That is also exactly what the rebuttal papers said of him. That's the process of science. By the way, in case you think that "two guys" can't trivially disprove the entire physics community there was this unknown guy with the name of Albert Einstein who worked at a patent office...
The "Torah", the laws written on large scrolls, do not have vowels on them. "Torah", meaning "Law", is the basis of the Hebrew Testament. They are copied from scroll to scroll by a scribe who needs to do it PERFECTLY - one mistake, which may include ink from one letter touching another, renders the entire thing void and invalid (and requires its destruction, no less). Fortunately, Torahs are written on multiple pieces that are stitched together (with ligaments, if memory serves) and the 'offending' piece can me taken out and replaced.
The vowels that people here are talking about are in the Chumash, a book that was created so that the Torah can be followed along with. The Chumash also contains insightful commentary from one or more sources, explaining certain ideas and translations more fully. Also, a Chumash will often have Hebrew on one page, and English (for example) on the opposite page, so that people can learn the stories without requiring Hebrew as a primary language.
The "Hebrew Testament" was translated into Greek, and then into Latin, if memory serves. These translations often contained errors that have made it into the Christian 'mainstream' ("Splitting the Red Sea" never happened, for example. It was the "Sea of Reeds", according to the original Hebrew).
Ergo:
killing without religious sanction - bad
mass murder whenever God changes his mind about the whole 'sanctity of all life' thing - good
Procrastination Man strikes again!
It's a nice article abouw a new formula, but they forgot one minor detail: the formula. Or is it patented already?
"an idiot of the highest order" isn't an ad homenim attack eh?
While you might seem to know something about physics you also evidently have a need to personally attack those who argue and challenge your statements by reverting to the time honored practice of name calling.
The Magic of The Amazing Randi has more reality to it than Dark Matter.
I suppose that you believe in God as well as Dark Matter?
I agree with the grandparent, and disagree with you.
There's no governing body of scientific terms, but I've seen many proposed laws with no prior history of being called a theory. In my physics experience, laws are almost always a mathematical model of observed behavior with no attempt to explain the underlying reasons or mechanics of said behavior.
Laws are theories as they fit all the definitions of a theory, but they don't become laws by extra proof, rather by their initial limited nature. For example, there is a law of gravity ( F = G Ma Mb / r^2 ) and there are separately various theories of gravity such as general relativity.
-Ryan C.
It is *always* wrong to initiate the use of force against another person. The only time that the use of force is justified is to defend oneself or another against a person who has initiated the use of force.
In other words, it's not OK to shoot a burglar until after he stabs one of your kids?
If a person refuses to pay taxes, or to join the government's health care plan, the government compells them by threatening jail. If they resist jail hard enough, they are killed instead, by the government, i.e. other people. Is that murder? Why not? And don't hide behind the the fraud that murder is only the "unlawful" killing of someone.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Dark Matter exists, and in my opinion it is here for good. The attempts to come up with alternative theories of gravity are quite noble, but they only work on certain scales, and the proponents of these theories sometimes neglect examples that invalidate their theory. It would be quite elegant to be able to account for dark matter via a modification of gravity alone, but I am afraid that it will not be possible.
One of the most compelling pieces of evidence for the existence of dark matter is the "bullet cluster of galaxies" discovered by Maxim Markevitch and collaborators. Their 2004 peer reviewed article shows a small cluster of galaxies passing through much more massive one. As the cluster passes through, its gas is stripped, but the dark matter stays behind, detected via weak gravitational lensing. This effect is impossible to reproduce using alternative theories of gravity, because there is a visible separation between the total mass peak and the observable mass peak.
There are dozens of other peer-reviewed articles that argue against these alternative theories of gravity. What about the cosmic microwave background? The CMB is one of the underpinnings of modern cosmology and basically made the big bang the widely accepted theory that it is today. This recent analysis of the CMB show that the kind of alternative gravity proposed here is strongly disfavored by the CMB spectrum, and that it would imply too high a neutrino mass.
I challenge you to look through the literature for yourself. Here is a list of papers discussing modified newtonian gravity and its derivatives... You will find that yes, these alternative theories do work quite well at describing the rotation curves of galaxies, as TFA suggest. But on larger scales, such as in cluster of galaxies and the cosmic microwave background, they seem to fail convincingly.
Hm. Interesting postulations. Iron does not fuse very well and if it were fusing in our sun, we would see more evidence of it. What you say sounds reasonable otherwise.
strike
"Someone needs to talk to the tree of liberty about its ghoulish drinking problem." by ohnocitizen
And just to show how the Law of Unintended Consequences works, if Saul had obeyed, Hamen would never have been born, the Book of Esther would never have been written and Purim wouldn't be celebrated. Not only that, we wouldn't have delicious humentashen to eat, and that would be a real shame!
Good, inexpensive web hosting
Murder is the premeditated intentional killing of another person. A soldier killing another soldier in a war is not murder because the aim is not to kill soldiers. A lot of people don't understand this, but the goal in war is not supposed to be to kill the enemy but to achieve some objective, usually economic. Killing tends to be necessary, but it is not the goal, thus the killing is not premeditated and intentional.
Now, if you're fighting a "war" where you want to kill the enemy (usually this develops into genocide) then yes, you are committing murder. A soldier sent on an assassination mission is committing murder. Whether murder is justified in some situations is a moral question, but that doesn't make it something other than murder.
If you have a reasonable fear that the burglar will harm you or your family then that is self defense. It's murder to shoot him in the back as he runs away though, even if he does happen to be in your living room at the time. Or as he raises his hands and surrenders.
If you have a reasonable fear that the burglar will harm you or your family then that is self defense.
So if you have reasonable fear that a country will harm you or your allies, then it's self defense to invade them, depose their government, and set up a new government less likely to attempt to harm you.
Yes, you could argue that. I might modify that to say if you have a reasonable belief that a country poses an imminent threat to you or another country then it is self defense to remove that threat using minimal force.
So I would say using force to liberate Kuwait was morally justifiable. Invading Afghanistan was morally defensible. Invading Iraq, deposing their government and setting up a new government... less so.
you made a dumb assertion and got called on it
There you go again with the personal attacks and name calling. If I was to stoop to your level I'd have to say something like "wash your mouth out with some dark matter". However, I won't stop to your low level.
I actually have proven my argument: you were totally ignorant of the rebuttals of Cooperstock and Tieu's paper even while citing their paper as dispensing with dark matter.
You've not proven your argument. You are assuming that the rebuttal papers are conclusive in dispensing with the Copperstock and Tieu line of reasoning. That's a big leap. They have opened a new door, a new possibility that others have rejected. Maybe it will lead nowhere but it's an open possibility that will need to be fully explored and a few rebuttal papers are NOT necessarily the end of it.
"Yeah, I am so terribly concerned with pleasing you, Mr. Anonymous CuttingEdge."
I already addressed the advantages of Slashdot accounts that do provide some identity presense which you seem to reject out of hand Anonymous Coward.
You assume that a comparison of Dark Matter with Magic is bad.
The Amzaing Randi can present conclusive proof that Magic is real, which is a lot more than you can say about Dark Matter with it's "strong evidence".
Your linked posting, which you can't prove is yours since you've posted it anonymously, wasn't relevent to my posting since the linked posting didn't provide conclusive and extraordinary proof.
I didn't attack your request for "extraordinary evidence". In fact, I gave you quite a bit of evidence.
But you didn't present extraordinary evidence. As Carl Sagan said "extraordinary claims require extraordinary evidence."
Dark Matter doesn't need to have been "proven" to require the production of extraordinary evidence. The fact that the Dark Matter hypothesis makes extraordinary claims is enough to trigger the requirement for extraordinary claims.
"The existence of dark matter will be resolved by a new theory driven by new experimental evidence. It won't be because physicists have been misapplying existing theories all along due to math errors.
Maybe, maybe not. You don't know that for sure unless you can travel into the future or see into a crystal ball. In fact your statement is a belief.
"If it's a different question, than why did you cite C&T in support of your claim regarding physicists making math errors?
Obviously you need to re-read the paragraph untill you understand what it's saying. Let me be very clear: You are assuming that the rebuttal papers are conclusive in dispensing with the Copperstock and Tieu line of reasoning. That's a big leap. They have opened a new door, a new possibility that others have rejected. Maybe it will lead nowhere but it's an open possibility that will need to be fully explored and a few rebuttal papers are NOT necessarily the end of it.
You "believe" that they made errors. Reading the papers it looks that way. However it's not the end of that line of reasoning you'll have to admit.
For a time people thought that Einstein made a big mistake with his Comological Constant, he also beleived that it seems. Now it could be that he was on to a line of reasoning that while not entirely correct is reaping large rewards. Who are you to judge Cooperstock and Tieu and dispense with their work with a lot of sound, fury and insults? Aspects of thieir work could prove valuable.
Belittling them is an ad hominem attack. Belittling them lowers the quality of your work. It's a favorite method of arguing of yours. It's likely that you use it in your life with many of the people around you. Satisfying is it?
My response to ad hominem attacks is too point them out to the person who makes them rather than replying in kind. Please raise the quality of your discussion.
By stating that Cooperstock and Tieu are just "two guys" you do them a diser
Into which category would you place WWI and WWII, then?
That's a pretty broad question. I'll assume you're talking about US involvement in those wars? If so, then we were aiding in the defense of the Allied nations against German aggression, no? We did not start either war; i.e. we did not initiate the use of force.
Downmodding is the refuge of the weak. Don't downmod, make a better argument!
In other words, it's not OK to shoot a burglar until after he stabs one of your kids?
IMO, the burglar initiated the use of force at the point at which he pulled out the knife.
Downmodding is the refuge of the weak. Don't downmod, make a better argument!
We all know murder is wrong, I was talking about killing. Which I would also think is wrong, but apparently it's allowed sometimes, like in self defence as you say. Going into Iraq isnt exactly self defence though, unless I guess you count the whole of humanity as 'self', and then defend yourself when you are oppressed. Or if you count defending your interests (in this case oil) as self defence?
I'm not sure whom you're asking but - I certainly don't consider the invasion of Iraq to be an act of self defense. At the time of the invasion, Iraq posed no overt, imminent threat to the US or any other nation. The Bush Administration may claim that they thought Iraq posed an imminent threat, but 1) the largest intelligence organization in the world should not have made such a mistake, and 2) I don't think it was a mistake; I think Bush just wanted to invade Iraq, plain and simple.
Downmodding is the refuge of the weak. Don't downmod, make a better argument!
Back in the real world, does the world now bomb Iran? Real world, pal. Answer? Taking your time to answer means no.
Now? No. Why? What legitimate justification is there?
Downmodding is the refuge of the weak. Don't downmod, make a better argument!
"No, it's an insult.
Embedded within an argument or not an insult is a form of personal attack. It simply indicates the low quality of your arguments.
I laid out the extensive scientific support for the theory -- and, as I offered earlier, I can point you towards review articles with much more evidence.
As you yourself stated the evidence isn't conclusive.
Wow, that's a convincing argument.
Obviously you missed the point about the comparisons with Magician's Magic being real and Dark Matter being a hypothosis.
The scientific basis for calling the Dark Matter mythical magic is that it's not yet been proven conclusively. It's still a theory in the works, a hypothosis without substantial evidence of the extraordinary kind to support the extraordinary claims made by it's Dark Matter hypothesis.
You've won nothing. You've missed the point completely. It seems that since you don't get what I was saying you revert to calling me names rather than asking pertinent questions. Up the quality of your discussion, stop insluting people. Reread what I've written and see if there are other meanings that you missed on prior readings. You might learn something.
Save some face and admit you've been making a fool out of yourself. You're not going to hide your ignorance by attacking me.
I'm not attacking you. I'm pointing out where you are attacking me. Am I a fool for pointing out that Dark Matter is still simply a hypothesis with some evidence and in that regard it has aspects of similarity with Magicians Magic and Mythical Magic? Am I a fool for pointing out that you are using personal attacks in your arguments? Am I a fool for letting you know that it's possible that there could be alternative explainationsof reality that don't resort to the use of what is essentially Magical Dark Matter (remember it's not yet been proven that Dark Matter exists)?
Could it be that you missed the points that I've been making? Yes it could be.
Okay. I shall henceforth refer to it as the Commandment of General Relativity.
I said there is not a need for extraordinary evidence, because that kind of evidence is only required to justify "conclusively proven" claims.
Yes, it's obvious that you said there is no need, however that's nonsense. The Dark Matter hypothesis makes claims that require extraordinary evidence beyond the "strong evidence" obtained so far.
Obviously this is a point where we disagree.
In your other points you are simply repeating yourself or stating obvious facts about science and the Dark Matter hypothesis. Oh, ya and you continue with your insulting ways. You also seem to enjoy twisting statements to extreme points of view that do not actually reply to what I said, in essense taking the points out of context.
You also seem to be shifting your point of view on the "strength" of the Dark Matter hypothesis stronger and stronger.
My posts have been appropriate responses to what you've posted. However, you keep missing the points in the posts and are constantly using insults, belittling statements, ad hominem attacks (contrary to your statements that you've not used them), personal attackes, etc... against me and the scientists mentioned. By any assessemnt you would be well servered to alter your approach.
If you look at the forum history you will see that you are using personal attacks. All I did was point out that fact. Pointing out that you use personal attacks is not a personal attack since I'm repectfull, have not called you names, and have asked that you stop such comments in the discussion. Your counter that these comments are themselves personal attacks against you is silly since it's clear that you are the one making the insults and attacks.
I hope that you will reconsider your usage of the illegimate argument devices and stop using them. Then maybe we can continue a civil discussion.
First, and glaringly....you said:
about scales, from TFA:
A non-Newtonian gravity theory is now fully specified on all scales by a smooth continuous function.
so, this yet to be reviewed theory claims to have overcome your first objection, and you cannot prove them wrong until April.
you said:
ok, so no theory that you have seen can explain gravity better than dark matter without being REALLY contradictory to observations. Yeah, you know what I'm going to say...it is possible this new theory can do what you say it can't...which brings me to:
overall, i think you're wrong when you say dark matter absolutely must exist. Supposedly, this theory can explain gravity in a way that somehow changes predictably on different scales.
IANAA, but judging from the new kuiper belt object xena, I think the Oort Cloud may be the beginning of a new understanding of what it is exactly that lies between us and our nearest neighbors...on all scales. I think it's possible we will eventually observe many more such objects. While it may sound as if I'm supporting a dark matter theory, no...I am merely stating that neither dark matter nor this new theory will be the last, simplest theory of gravity. Dr Fameay from TFA would agree:
It is possible that neither the modified gravity theory, nor the Dark Matter theory, as they are formulated today, will solve all the problems of galactic dynamics or cosmology. The truth could in principle lie in between, but it is very plausible that we are missing something fundamental about gravity, and that a radically new theoretical approach will be needed to solve all these problems. Nevertheless, our formula is so attractively simple that it is tempting to see it as part of a yet unknown fundamental theory. All galaxy data seem to be explained effortlessly
Thank you Dave Raggett
"Preferred" does not mean "stand back and get beaten up", it means what it says. If there is an option by which nobody gets hurt, that should be considered (not "required", considered) first.
"Well, yes," you might say, "so if we all drive around in armoured, bullet-proof cars, wore chainmail armour and had a forcefield generator in a pocket, we'd be a lot safer. And how likely is that?"
With the exception of the forcefield, I don't see anything there that is so totally impossible that it simply cannot be done. You wouldn't use medieval chainmail, but you don't need medieval materials or design requirements, there not being many people with broadswords and maces walking around, and material science is a damn sight more advanced today. I'm also talking about a direction, not a specific point in time. If it's not viable today, then do your best today and see what you can do in ten years time, or a hundred years time. The idea that offence is the ONLY defence is not going to be valid for all time and may not be valid in many situations today.
I see no reason why society persists in limiting itself to 12th century methods, using 16th century tools, of handling 21st century threats which are likely as bad as they are due to 1st century attitudes. There almost has to be better methods of dealing with things, regardless of whether those methods are known today.
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)
The only time that the use of force is justified is to defend oneself or another against a person who has initiated the use of force.
Well yeah, but good luck finding a definition of "initiates" that most people will agree with. Will cause violence? Has caused violence? Is presently causing violence? Incited/inciting/will incite violence? If someone punches you and runs away, is the fight over? What if they do it again the next day? If drawing the lines between defense, retaliation, and protection was easy, we'd have far less violence in the world, unless you believe that most people use violence for its own sake.
https://www.eff.org/https-everywhere
Eintein's theory certainly have improved the understanding of universe but since then, he did not really care about the gravity afterwords because he wa busy fighting and biting against Neils Bohr and other quantum Physicist in Europe. If there is any theory that uses Einstein's version of gravity (space time fabric), that would be String Theory. Remember, G(mu)(nu) is equal to 8(pie)-1/2 times g(mu)(nu).
Firstly, I'd been under the impression that some galaxies behaved differently ( because the "dark matter" had been stripped out from them, or otherwise relocated, or something, in intergalaxy-collision ), and this was part of the validation of the "dark matter" idea, AND
Why in hell does everyone call it Dark Matter, when it is Dark Mass, but with n-1 .. 1 ( or 0? ) dimensional branes ( assuming n dimensions ), rather than "particles", so the term "matter" builds assumptions that enbogify our understanding from the get-go?
Eh?
IPTables enhancement Fail2Ban bans cracker-login's
Unlike some gun happy home owners a thief is not automatically violent, I'm sure most courts would find a hole in the head in exchange for stealing a dvd player seems a tad extreme. If you read the GP's statement that you quoted you would see you don't have to wait until your kid gets stabbed. It's ok to shoot a thief if you have a reasonable belief the aggressor is about to hurt you or your kids.
I would also posit that a soldier is carrying out the demands of his nation as a duty, war and execution are very different circumstance to murder. The politicians may be justifyably be seen as "murderers", but the soldier and executioner are just instruments of government policy.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Of course the killing is intentional, if you pull the trigger on purpose.
It may not be premeditated, but also I dont see how if you are at war then I dont see the difference between someone sneaking to a camp to assassinate a leader, than killing soldiers on the battlefield. Less people are likely to die if there is no leadership, they are more likely to scatter or have their morale lowered and surrender, etc..
which is totally what she said
And we have a winner. I was cringing while waiting for this arrogant remark, though hoped nobody would be dumb enough to present it. (And when I say "arrogant", I am referring to the human condition as a whole rather than individual myopia.)
Gravitational microlensing only works if there happens to be a lighted star between the observer and the subject, (a tiny little degree just off to one side, to be precise). Observational constraints indeed! Gravitational microlnsing is a clever way to prove the existence of brown dwarfs, not a way to perform a full spectrum 'scanner' sweep capable of mapping the heavens.
There is a whole lot of matter out there which is simply not illuminated. Period. The "Missing Matter" needn't be described by magical non-particles which, (ahem) have never been observed, and which make a lot less sense than the lights simply being out.
It strikes me that this is further evidence that it is the social acceptability of an idea which determines its Lemming-Magnet factor rather than the actual rationality, or in this case, the irrationality behind it.
That is, I thought serious scientists looked down their noses at things like ghosts. (Which is, of course, equally short-sighted of them.)
-FL
I read that line and immediately pictured astronomers flying around randomly.
Then I imagined a silly thought experiment. If a bunch of non-Einsteinian gravity astronomers were in an elevator and it dropped, would they just fly/bump around the elevator in random directions?
The soldier on a battlefield has an objective. Say, "take that hill." In doing that, he may come under fire, or have a reasonable expectation that he will come under fire from an enemy soldier. If he kills that soldier, you can look at that as him defending himself. Now, if that enemy is unarmed, or surrenders then our soldier no longer has a reasonable expectation that he's in danger, so killing the enemy would unquestionably be murder. It's a subtle difference, but it is real. No comment on the morality of fighting in a war.
An assassin has the specific objective of taking a life whether or not that target presents a direct threat to him. That's the difference. A regular soldier would be quite happy to achieve his objective with no life lost, on either side. An assassin cannot achieve his objective without killing.
Actually, historically taking out the leadership was an extremely bad idea and was taboo. War used to be more an attempt to beat the enemy into surrendering. Surprisingly few lives were lost. If you take out the leader, the enemy can't surrender, so a bloodbath ensues.
"A regular soldier would be quite happy to achieve his objective with no life lost, on either side."
"If you take out the leader, the enemy can't surrender, so a bloodbath ensues."
I'm sure there's a point in there somewhere that shows that if you take out the leader, then the enemy would be more willing to surrender. Unless you're talking about a war over land and not some stupid economic factor like oil. I guess I always think of one side in a war as being the good guys, and that the opposing/evil side will actually benefit from losing, but I guess that doesnt have to be true.. in Iraq for example though, a lot of people I'm sure dont like Sadam and would be happy to get him out of power and have a more western style political culture instated.. *shrug*
which is totally what she said
and yes I know Sadam is out of power, but I mean in general people aren't going to complain if a dictatorship is broken (apart from the trains not running on time..)
which is totally what she said
Things are a little confused because nobody's really fought a classic
"honorable" war since WWII. Take Iraq for instance though. If the two sides were equally matched, Saddam stood up and fought, there was a decisive battle and he lost, do you think it would be better if he were dead, there's no leader to surrender, so resistance forces go guerilla, OR he's alive to say "hey guys, we're beaten, let's pack it in?"
When ships used to fight by peppering each other with cannon balls then boarding, the fight was over when one struck her colours. Usually that would happen as soon as one captain realized that he couldn't win. If he were dead, unless he had a particularly enterprising lieutenant, the battle would just go on until the losing side simply couldn't fight any more.
Everybody things their side in a war is the good guys.
You'd be surprised. We live in a democracy so we think it's the best way. Lots of places that live under dictatorships or other totalitarian rule defend it vigorously. Look at the Soviet Union. It was only when things fell apart economically that they ditched the politburo. There are still a lot of people who would bring the old system back into power. Cubans were not pleased when the US invaded and tried to "free" them from their dictator.