Gas rich galaxies confirm prediction of modified gravity theory

Feb 23, 2011
Gas rich galaxies confirm prediction of modified gravity theory
The star dominated spiral galaxy UGC 2885. Image by Zagursky & McGaugh

(PhysOrg.com) -- Recent data for gas rich galaxies precisely match predictions of a modified theory of gravity know as MOND according to a new analysis by University of Maryland Astronomy Professor Stacy McGaugh. This -- the latest of several successful MOND predictions -- raises new questions about accuracy of the reigning cosmological model of the universe, writes McGaugh in a paper to be published in March in Physical Review Letters.

Modern cosmology says that for the universe to behave as it does, the mass-energy of the universe must be dominated by and . However, direct evidence for the existence of these invisible components remains lacking. An alternate, though unpopular, possibility is that the current does not suffice to describe the dynamics of cosmic systems.

A few theories that would modify our understanding of gravity have been proposed. One of these is Modified Newtonian Dynamics (MOND), which was hypothesized in 1983 by Moti Milgrom a physicist at the Weizmann Institute of Science in Rehovot, Israel. One of MOND's predictions specifies the relative relationship between the mass of any galaxy and its flat rotation velocity. However, uncertainties in the estimates of masses of stars in star-dominated spiral galaxies (such as our own Milky Way) previously had precluded a definitive test.

To avoid this problem, McGaugh examined gas rich galaxies, which have relatively fewer stars and a preponderance of mass in the form of . "We understand the physics of the absorption and release of energy by atoms in the interstellar gas, such that counting photons is LIKE counting atoms. This gives us an accurate estimate of the mass of such galaxies," McGaugh said.

Using recently published work that he and other scientists had done to determine both the mass and flat rotation velocity of many gas rich galaxies, McGaugh compiled a sample of 47 of these and compared each galaxy's mass AND rotation velocity with the relationship expected by MOND. All 47 galaxies fell on or very close to the MOND prediction. No dark matter model performed as well.

"I find it remarkable that the prediction made by Milgrom over a quarter century ago performs so well in matching these findings for gas rich galaxies," McGaugh said. "

MOND vs. Dark Matter - Dark Energy

Almost everyone agrees that on scales of large galaxy clusters and up, the Universe is well described by dark matter - dark energy theory. However, according to McGaugh this cosmology does not account well for what happens at the scales of galaxies and smaller.

"MOND is just the opposite," he said. "It accounts well for the 'small' scale of individual galaxies, but MOND doesn't tell you much about the larger universe.

Of course, McGaugh said, one can start from the assumption of dark matter and adjust its models for smaller scales until it fits the current finding. "This is not as impressive as making a prediction ahead of [new findings], especially since we can't see dark matter. We can make any adjustment we need." This is rather like fitting planetary orbits with epicycles," he said. Epicycles were erroneously used by the ancient Greek scientist Ptolemy to explain observed planetary motions within the context of a theory for the universe that placed the earth in its center.

"If we're right about dark matter, why does MOND work at all?" asks McGaugh. "Ultimately, the correct theory - be it dark matter or a modification of gravity - needs to explain this."

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More information: Preprint of original paper on arXiv.org

Read more about dark energy and dark matter on this NASA Web page

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dogbert
3.1 / 5 (33) Feb 23, 2011
"If we're right about dark matter, why does MOND work at all?"


Because, of course, we are not right about dark matter. Dark matter as a concept was created from nothing as a correcting factor to our theories of gravitation which failed to predict the motions of stars and galaxies. It never had a basis in fact and still does not.

MOND begins with the acceptance that our theories are not capable of describing gravity on galactic scales and modifies the theory itself to account for the observations.

Careful observation and modification of theories trump fantasy.

As the article expressed it, dark matter "is rather like fitting planetary orbits with epicycles".
kaasinees
1.5 / 5 (30) Feb 23, 2011
I never believed in darkmatter, the concept is ridiculous. But that doesnt mean there are particles that we dont see, which what dark matter originally meant. Than psuedo-scientists started accounting dark matter for keeping galaxies together etc.

Most people that are called scientists today are not scientists at all...
dogbert
2.6 / 5 (29) Feb 23, 2011
Most people that are called scientists today are not scientists at all...


Not a bad observation. I would restate it thus:
"Many people who claim to be scientists today are not scientists at all..."

It is instructive to observe how many people who claim to be scientists or scientific on forums such as this who cannot use basic logic or perceive basic logic errors.
Waterdog
4.5 / 5 (21) Feb 23, 2011
"The universe is not only stranger than we imagine, it is stranger than we can imagine" - Albert Einstein. That being said, we have some pretty strange people doing the imagining.
Nichol
3.5 / 5 (19) Feb 23, 2011
This article has an attractive title, but never says what this modified gravity theory predicts. Nor which are the observations that are allegedly not so well described by dark matter & dark energy.

The comparison with epicycles at the end makes no sense. Apart from that, the author is clearly ignorant about when and how the original epicycles were conceived. Epicycles were invented long before Ptolemy, and within the observational accuracy of the times, they did describe wobbles in the orbits of the moon and the planets quite well: good enough for the Antikythera mechanism to be not a bad predictor of eclypses.
Moebius
1.8 / 5 (22) Feb 23, 2011
Dark matter doesn't exist, our theories need to be modified, and that includes our ideas of time. Dark energy may also be an artifact of incorrect theories as well. If this was a post instead of an article it would get the usual 1's from the physics primadonna's, like all those at physicsforums, who can't stand having their cherished dogma questioned.
DrDeth
5 / 5 (11) Feb 23, 2011
Why is there so much spam in the comments on this site?
antialias
4.8 / 5 (25) Feb 23, 2011
It doesn't matter whether you believe or don't believe in dark matter (or whether you find it 'plausible' or not). The best theory is the one that makes the best predictions. Period.
Johannes414
4.2 / 5 (14) Feb 23, 2011
The best theory is the theory that does not need a whole list of fudge factors to artificially match the observations, according to Occams razor.
Quantum_Conundrum
2.3 / 5 (24) Feb 23, 2011
It doesn't matter whether you believe or don't believe in dark matter (or whether you find it 'plausible' or not). The best theory is the one that makes the best predictions. Period.


Dark Matter doesn't predict ANYTHING.

Dark Matter and Dark Energy are constantly being used as an arbitrary PATCH to explain why mainstream theories FAIL to predict galactic and intergalactic motion.
Shootist
4.4 / 5 (19) Feb 23, 2011
It doesn't matter whether you believe or don't believe in dark matter (or whether you find it 'plausible' or not). The best theory is the one that makes the best predictions. Period.


Testable, with repeatable results.
Nik_2213
3.4 / 5 (7) Feb 23, 2011
Worst case could be that *both* 'MOND' and 'Dark Matter (DM)' apply in different cases. Some galaxies seem to manage without a 'fix', others seem to need a subtle tweak of Newton's classic laws...

Personally, I would prefer MOND to DM, but only because DM has so far failed to show itself in accelerators etc...
NotAsleep
3.2 / 5 (6) Feb 23, 2011
Perhaps what we'll find is that MOND fits after factoring in the near-gaurantee that we haven't detected all the baryonic matter in the universe. If we haven't proven or disproven massive objects in the theoretical Oort cloud, it would reason that a lot of the "missing" mass, currently called dark matter, in the universe is likely to be "standard" baryonic matter
Noumenon
4.5 / 5 (73) Feb 23, 2011
Dark Matter doesn't predict ANYTHING.
Dark Matter and Dark Energy are constantly being used as an arbitrary PATCH to explain why mainstream theories FAIL to predict galactic and intergalactic motion. - QC


Dark Matter and Dark Energy are not duck tape used to amend a broken theory. That is an unscientific perspective, and as such can not be productive. The correct view is that General Relativity PREDICTS the existence of more mass than is currently detectable, and also a vacuum energy density. If it is shown that no such things exist, then and only then, will GR be shown to be inaccurate. You can't just arbitrarily toss GR away because it is so accurate locally. Physics history has many examples where entities were theoretically predicted to exist before actually being observed.
Tissa_Perera
2.3 / 5 (9) Feb 23, 2011
McGaugh is right to pursue MOND and I give the reason for MOND to exist at cosmicdarkmatter.
Tissa Perera
Pyle
4.2 / 5 (13) Feb 23, 2011
This article has an attractive title, but never says what this modified gravity theory predicts. Nor which are the observations that are allegedly not so well described by dark matter & dark energy.


Read QC's comment. He got it right. Einstien/Newtonian gravity doesn't work without dark matter. Dark matter is inferred to make the formulas work. MOND predicts the shape and rotational speed of galaxies without dark matter. MOND, however, is not a relativistic theory, in my understanding. It says, use this other formula after a certain distance from a large mass.

1/3
Pyle
3.4 / 5 (8) Feb 23, 2011
The comparison with epicycles at the end makes no sense. Apart from that, the author is clearly ignorant about when and how the original epicycles were conceived. Epicycles were invented long before Ptolemy, and within the observational accuracy of the times, they did describe wobbles in the orbits of the moon and the planets quite well: good enough for the Antikythera mechanism to be not a bad predictor of eclypses.


The reference to Ptolemic epicycles DID make sense. Adding epicycles to the orbits of planets and celestial bodies was the response of supporters of the "standard" Ptolemic model to alternate theories, aka Copernicus. The analogy fits. The standard model doesn't work, let's add something that makes it work. This isn't bad. Sometimes wrong, but not bad.

Noumenon:
Saying GR predicts dark matter is only semantically correct when we find that dark matter actually exists.

2/3
kshultz222_yahoo_com
2.2 / 5 (12) Feb 23, 2011
I agree with the posts here. I never believed in Dark matter/energy.

A lot of scientists are going to be feeling really foolish when those ideas are totally debunked. They really should have (and many may have) known better. Of course, this is opinion at this point. The facts will come out eventually.
Pyle
3.9 / 5 (10) Feb 23, 2011
An alternate to MOND is MOG. Somebody on this site recommended Moffat's MOG theory and his book 'Reinventing Gravity'. Somebody else said it would collect dust on the shelf. Both right, but I recommend checking it out, your library should have it.

MOG 'predicts' a fifth force rather than dark matter to explain large scale cosmological phenomenon. MOG is a complete relativistic theory. MOG and MOND are very similar at larger scales, but MOG supporters feel it is more complete.

Is it better to add a fifth force or dark matter? Momentum in the scientific community is towards dark matter because it had a head start. Time will tell which plug is better. In either case it is science at work, predicting something and searching for ways to support the hypothesis.

Noumenon
4.7 / 5 (51) Feb 23, 2011
Noumenon, Saying GR predicts dark matter is only semantically correct when we find that dark matter actually exists.- Pyle


[...]In either case it is science at work, predicting something and searching for ways to support the hypothesis. - Pyle


Right.
Pyle
4.5 / 5 (14) Feb 23, 2011
Oh, I'm post happy again today...

Neptune was a plug to explain the motions of the other planets. So was the planet Vulcan. One worked. One didn't. Observe, predict, test.
Crackpot
1.2 / 5 (6) Feb 23, 2011
My own ideas about gravitation ("planar gravitation") predicts different effects of gravitation in gas rich compared to star rich galaxies! The simple principles are described on classicalatom.blogspot.com. It would be cool if somebody cared to tell me if these ideas could possibly agree with MOND...
Tuxford
1.8 / 5 (14) Feb 23, 2011
LaViolette predicted the Pioneer Anomoly in the mid-eighties, later observed, and verified to within a factor of two to best data. Largely agrees with the MOND model. However, his model explains the mechanism; expressed as photon blue-shifting.

The Big Bang is fantasy. Galaxies fully formed to early. There is no time dilation of distant quasars. Stars move radially away from the center of our galaxy. Younger stars concentrated near center of M31. AGN's unlikely due to accretion mechanism. AGN's cycle off in thousands, rather than millions of years. No rotation detected in Sag. A. Event horizon nearly 1/2 predicted radius. Time to think different?
El_Nose
3.3 / 5 (19) Feb 23, 2011
All these people crying out in the wilderness -- "I never believed in Dark Matter!!"

Give me a break - you never had the scientific background to even have an opinion worth listening to. And me not being a physics major i had no opinion either -- but at least i know my opinion on moderately high physics means nothing. Get on a forum type your thoughts and waste everyone's time.

Why didn't you believe in dark matter ?? because ....

Well dark matter was/is a logical conclusion to solve the problem of galaxy rotation. WHY?? because the theory held up in EVERY OTHER OBSERVABLE CASE!!!! dark matter is a solution to a problem that arises from a theory that has never been debunked.

and for those upset at this rant remember - Dark matter is a solution, not a theory. There was nothing not to believe.

Very few people were/are smart enough to try to rework the entire theory of gravity, and none of them subscribe to PHYSORG.

Rate me a 1. Cause this is just above your head
that_guy
4.1 / 5 (9) Feb 23, 2011
"If we're right about dark matter, why does MOND work at all?"


Because, of course, we are not right about dark matter. Dark matter as a concept was created from nothing as a correcting factor to our theories of gravitation which failed to predict the motions of stars and galaxies. It never had a basis in fact and still does not.

MOND begins with the acceptance that our theories are not capable of describing gravity on galactic scales and modifies the theory itself to account for the observations.

Careful observation and modification of theories trump fantasy.

As the article expressed it, dark matter "is rather like fitting planetary orbits with epicycles".


*Ahem* Thank you. Just because we know more today than centuries ago doesn't make us perfect. Scientists who are unwilling to consider that they might be wrong are no better than those who thought the earth was flat.
that_guy
2.6 / 5 (5) Feb 23, 2011
All these people crying out in the wilderness -- "I never believed in Dark Matter!!"

Give me a break - you never had the scientific background to even have an opinion worth listening to. And me not being a physics major i had no opinion either -- but at least i know my opinion on moderately high physics means nothing. Get on a forum type your thoughts and waste everyone's time.


Certain logic doesn't need a scientific background, just a little bit of knowledge. It would be unhealthy not to be a little skeptical when the scientists themselves admit that dark matter is a name to explain the unexplainable. The situation is quite clearly that they do not know what causes the effect. The reason for them to prefer it is because they have to mess with a core tenent of physics, or invent something new. Scientists are loath to mess with newton/einstein because they were so accurate...but not necessarily flawless.
that_guy
2.5 / 5 (16) Feb 23, 2011
If you replaced "Dark Matter" and "Dark Energy" with "God", the only thing that would change is the name. The evidence no more supports the current scientific thinking on it that it does God. Research and chew on that for a bit.

A broken clock is right twice a day, and so is QC this time around.
Silverhill
3.8 / 5 (15) Feb 23, 2011
[Waterdog] "The universe is not only stranger than we imagine, it is stranger than we can imagine" - Albert Einstein.
Actually, it's "The universe is not only queerer than we imagine, it is queerer than we *can* imagine." by J.B.S. Haldane. But the sentiment is quite true, regardless!

[Tuxford] The Big Bang is fantasy.
The cosmic microwave background would tend to disagree with you.
Galaxies fully formed to[o] early.
Support this notion, please. What do you know about what should have been the rate of formation?

Stars move radially away from the center of our galaxy.
And the galaxy has not therefore dispersed into a thin, unbound cloud of stars because...?

Time to think different[ly]?
Possibly so. Go ahead....
Tuxford
1 / 5 (11) Feb 23, 2011
Silver,
Check my comments from "Spitzer sees shrouded burst of stars", on Nov. 23rd, last year. This will get you started. It is hard to see the obvious, after decades of teaching the opposite. Most rationale minds just can't go there yet. Yet, the masses are awakening. Just look at Libya today.
Jaeherys
4.6 / 5 (8) Feb 23, 2011
@that_guy
As for logic, a lot of times in science, what we "think" to be logical turn out to be exactly the opposite. Maybe too crude an example for physorg but applicable nonetheless is adding salt to ice water. You see the ice melt and *logically* it is getting warmer. Everything you've seen about ice melting says it's gotten warmer. It is only when you delve a little deeper (and some basic chemistry doesn’t hurt!), that you would realize that it is the exact opposite; the ice has cooled!
In relation to dark matter, we can see the gravitational effect on galaxies akin to we can see that indeed the ice is cooling but unlike the ice, we don’t really know what the exact culprit is.
More than just knowledge is required to make logical predictions, experimental evidence + theory is a good place to start though.

Jake
Jaeherys
5 / 5 (1) Feb 23, 2011
My previous post was too long so it starts off sort of weird with "As for logic". I'm tired, and I can't seem to edit it, oh well! But I also said,

So I'm guessing this theory can explain,

httpDELETE://www.universetoday.com/502/galaxy-collision-separates-out-the-dark-matter/

and

httpDELETE://eands.caltech.edu/articles/LXX1/darmatter.html.
soulman
4.6 / 5 (11) Feb 23, 2011
It's funny to read some of these comments from people that don't like dark matter because they see it as a kludge, and then jump on the MOND bandwagon to explain it away.

If they knew anything at all about physics they'd realize that MOND is the ultimate fudge factor! There is no underlying theory as to why gravity should behave differently at certain distances - none. It's just a case of let's mess with gravity equations until we get the results we're looking for.

Now, I'm not condemning that kind of approach per se, but it has to be consistent with the rest of known physics too! MOND isn't. They've been trying to make MOND work with relativity for decades, to no avail.

Never mind that there is extensive indirect observational evidence for DM through gravitational lensing maps. MOND simply has no theoretical nor observational basis.
TabulaMentis
1.8 / 5 (6) Feb 24, 2011
MOND simply has no theoretical nor observational basis.
This article states the following: "Recent data for gas rich galaxies precisely match predictions of a modified theory of gravity known as MOND."

The article goes on to say that MOND is accurate in structures the size of galaxies and smaller, so dark matter appears is still be alive and well.
Tuxford
1.1 / 5 (10) Feb 24, 2011
The article goes on to say that MOND is accurate in structures the size of galaxies and smaller, so dark matter appears is still be alive and well.


LaViolette's model includes photon red-shifting over inter-galactic distances, and blue-shifting within galaxies near the presence of matter. Fits both interpretations, dark matter and MOND.
soulman
4.8 / 5 (9) Feb 24, 2011
This article states the following: "Recent data for gas rich galaxies precisely match predictions of a modified theory of gravity known as MOND."

I know what it says, but as I said, the whole theory came about as a fudge to get rid of DM - there was no other reason for proposing it. Since it was originally proposed, DM's presence has been detected through indirect means, while MOND still cannot be reconciled with relativity, which is kind of a deal breaker in my book (and mainstream physicists).
The article goes on to say that MOND is accurate in structures the size of galaxies and smaller

Perhaps, perhaps not. I'm sure I could come up with some convoluted formula which would be equally applicable to some isolated subset of phenomena - so what? Unless it fits in with the rest of known physics, it's of little use.
dogbert
2 / 5 (7) Feb 24, 2011
soulman,
There is no underlying theory as to why gravity should behave differently at certain distances - none. It's just a case of let's mess with gravity equations until we get the results we're looking for.


Newtonian gravity theory does not explain why gravity should behave that way either. It was developed based on observance of the way gravity behaved.

Relativity theory describes gravity as a curvature of space, but it does not explain why mass curves space as it does.

In each case, the formula were developed to match the observed behavior.

MOND notes that gravity behaves differently on stellar scales and constructs a formula based on the observed behavior (just as Newton did).

Neither Newton, nor Einstein nor Milgrom identify the cause of gravity to develop a model of gravity. In each case, the model was developed to match the observation of the behavior of gravity.

It is not a kludge to say "This is what we observe. This formula describes the observations."
frajo
3.4 / 5 (5) Feb 24, 2011
Never mind that there is extensive indirect observational evidence for DM through gravitational lensing maps.
But neither theoretical nor direct observational evidence.
MOND simply has no theoretical nor observational basis.
GR is modifying Newtonian dynamics. But GR has a problem with ang. momentum (Wikipedia: "Einstein-Cartan") and lacks small scale (< 1 mm) measurements.
Galaxy clusters cause gravitational lensing but are not flat disks with ang. momentum. Galaxies and solar systems are flat disks with ang. momentum. We are dealing with two separate phenomena. The causes might not be identical.
The precession of Mercury's perihelion is explained by GR modifying Newtonian dynamics. It might be expected that the orbits of galactic components expose GR effects, too. But although galaxies are more massive than the Solar system nobody wants Newtonian dynamics in galaxies to be altered.

Physics: Looking in a dark basement for a black cat which might not be there.
soulman
4.6 / 5 (8) Feb 24, 2011
Newtonian gravity theory does not explain why gravity should behave that way either. It was developed based on observance of the way gravity behaved.

Relativity theory describes gravity as a curvature of space, but it does not explain why mass curves space as it does.

In each case, the formula were developed to match the observed behavior.

It's always about descriptions, not the whys, and in fact I did say that I didn't fault the principle used, PER SE.

You seem to be overlooking a huge Achilles heel of MOND, which I have repeatedly voiced, and just keep going on how it fits one particular case (of which I have doubts anyway). You can't just sweep inconvenient stuff under the (cosmic) rug, especially when the accepted alternative works better and has observational support.
It is not a kludge to say "This is what we observe. This formula describes the observations."

It is, in this case.
soulman
5 / 5 (8) Feb 24, 2011
But neither theoretical nor direct observational evidence.

How can you have 'direct' observational evidence of something that does not radiate and barely interacts with normal matter? One possibility might be CERN, so fingers crossed.

But WRT to indirect evidence, you simply can't explain the gravitational lensing sky maps in any other way, not with MOND, not with 'hidden' normal matter. Also, DM is required to get a universe to evolve into something which even vaguely resembles our universe. Even the article concedes that DM describes our universe extremely well.

If MOND is to have any chance at all, it will have to fit in with all aspects of known physics. If that can be done, absolutely fantastic - it will be a minor (major?) revolution in physics, but so far (and it's been around for a long while), it's a non-starter.
Aristoteles
1 / 5 (3) Feb 24, 2011
There are many other EPI-cycles in "modern physics":
-EPR epicycle,TOE epicycle,GravitoMagnetic epicycle,
Twin-epicycle,Red-shift and Doppler epicycle,
Dirac-sea epicycle { is there Black Dirac-Sea ...?),
BB-BCrash epicycle,Unruh-Hawking-El Naschie epicycle etc, etc...
A Merry SUSY and happy MOND+Higgs in White Flatland- Multiverse !
dogbert
1.5 / 5 (12) Feb 24, 2011
soulman,

Even the article concedes that DM describes our universe extremely well.


That is a major problem with Dark Matter. It is "found" in precisely the amounts needed in precisely the areas needed to make our failing models fit.

It is a perfect kludge in that it is defined as a substance which cannot be detected.

There is nothing logical or scientific about dark matter. It is a pure kludge which lets us avoid the very real failure of our current models.
jamesrm
2.3 / 5 (3) Feb 24, 2011
The main probelm MOND will have is it will make fitting Gravity into QM/String theory etc more difficult.

Dark Matter being presumed to be a particle (with lots of knobs to twiddle to fit observations) makes funding to find it in a a collider or similiar Earthly experiment available.

At least thats how it seems to me.

"But WRT to indirect evidence, you simply can't explain the gravitational lensing sky maps in any other way,"

You mean there is no >KNOWN< OTHER MECHANISM, weasle wording that implies we know all thats knowable do not belong in science, only religion.

rgds
jms
Pyle
2 / 5 (3) Feb 24, 2011
Why isn't anyone mentioning Moffat's MOG? Dr. McGaugh is even involved with his work. The formulas reduce to Einstein's for measurements in the solar system. It looks kind of like MOND at galaxy scales. It doesn't have any ad hoc variables like MOND. Why isn't it being talked about?

It is a relativistic theory that doesn't need dark matter. ???
soulman
4.9 / 5 (8) Feb 24, 2011
That is a major problem with Dark Matter. It is "found" in precisely the amounts needed in precisely the areas needed to make our failing models fit.

False. It was hypothesized to exist to explain galaxy rotation curves going back to Zwicky in the 30s, and later to the structure of the universe. The fact that it's been indirectly detected means in must have a physical reality. You can argue precise percentages and particular decimal points, but the fact remains, the evidence for DM is compelling (as opposed to fanciful).
It is a perfect kludge in that it is defined as a substance which cannot be detected.

Only to the uninitiated.
There is nothing logical or scientific about dark matter. It is a pure kludge which lets us avoid the very real failure of our current models.

Ditto.
soulman
5 / 5 (7) Feb 24, 2011
The main probelm MOND will have is it will make fitting Gravity into QM/String theory etc more difficult.

Nope. String theory is nothing more then pure theory, no evidence. QM isn't really relevant unless you're talking GUTs.
Dark Matter being presumed to be a particle (with lots of knobs to twiddle to fit observations) makes funding to find it in a a collider or similiar Earthly experiment available.

Ok...I think...if you mean CERN testable.
You mean there is no >KNOWN< OTHER MECHANISM,

Well, duh.
weasle wording that implies we know all thats knowable do not belong in science, only religion.

Get a grip, weasel boy. Are we to rule in Leprechauns too because we don't know they exist?
Pyle
1.8 / 5 (5) Feb 24, 2011
the evidence for DM is compelling

What evidence?
The evidence for DM is that GR has created a host of predictions that have proven true. In order for GR to work at the galactic scale dark matter needs to exist.

There is also the whole 4/25/70 postulate, but there are other explanations there.

What other dark matter evidence am I missing?
Pyle
2.5 / 5 (6) Feb 24, 2011
The main probelm MOND will have is it will make fitting Gravity into QM/String theory etc more difficult.

MOND isn't a theory. It is an equation change to fit with observed data. It really doesn't do anything with QM. As we get more quantum gravity theories it might play into testing them, but if dark matter exists, it won't.

String theory is, so far, unfalsifiable. Just some neat math with an infinite number of solutions, one or more of which, the supporters think can model the universe.
frajo
5 / 5 (6) Feb 24, 2011
String theory is, so far, unfalsifiable.
While I'm no expert on ST there is at least one ST-based, non-standard cosmology, the Steinhardt/Turok Ekpyrotic/Cyclic Universe, which does make falsifiable predictions concerning the WMAP polarization pattern components. Another testable prediction is the existence of extra dimensions.
Just some neat math with an infinite number of solutions, one or more of which, the supporters think can model the universe.
"Just some neat math" is not an appropriate notion of ST. We should not dismiss the potential of ST to be a worthy successor of GR and, possibly, the unique unified theory of all forces in nature.
Pyle
3 / 5 (5) Feb 24, 2011
frajo,
I agree. I was a little harsh and unnecessarily dismissive. But on the extra dimensions part, they're too tiny to detect, hence my unfalsifiable tweak. M-theory and branes/superstrings are promising and may provide a unique unified theory, but we really aren't there yet. So far I think we have narrowed it down to a little less than an infinity of possible solutions.

Basically, I dismissed it unecessarily, and I did it again. Hmmmm. Just can't make up my mind. Too many string theory books and too little apparent progress.
Pyle
3 / 5 (5) Feb 24, 2011
@soulman:
The fact that it's been indirectly detected means in must have a physical reality.

Just like Neptune. And Vulcan. So not so much... but maybe!
soulman
4.3 / 5 (6) Feb 24, 2011
What evidence?

What other dark matter evidence am I missing?

Honestly, sometimes I wonder why I bother to post stuff if people are simply going to ignore it. How many times need I mention gravitational lensing maps?

Here are some recent-ish findings:
hubblesite.org/newscenter/archive/releases/2010/37/full/

And here, a pretty good overview of the field, including dark energy:
rsta.royalsocietypublishing.org/content/368/1914/967.full

dogbert
1.6 / 5 (9) Feb 24, 2011
soulman,

The use of "Dark Matter" to explain gravitational lensing is not different from the use of "Dark Matter" to explain the rotation of galaxies. In both cases, gravity is observed to be stronger than our theories predict. Adding "Dark Matter" in both cases is just a kludge to make the observations match our theories.

No one has identified a single dark matter particle. If our galaxy has so much more dark matter than normal matter, you would think we would be able to find some of it close to home, wouldn't you?

Dark matter may well be the case, but its creation and the arguments for it are all just a way to keep our theories despite their failure to describe what we see everywhere we look.
Pyle
2.9 / 5 (8) Feb 24, 2011
I agree with dogbert, but he directed the comment at me so...

Honestly, sometimes I wonder why I bother to post stuff if people are simply going to ignore it. How many times need I mention gravitational lensing maps?

How is the dark matter postulated to exist to account for lensing any different than the dark matter postulated to exist to account for galaxy structure? Same evidence. They don't know how much dark matter is there until they see the lensing or rotation and then "fit" the dark matter to the observed result.
Is it really there? That is the guess. But we don't really have any evidence besides GR being very right in a lot of other tests. Is it the best guess we have right now? Probably. At least it is the most accepted and should be provable one way or the other. (Still post happy.)
soulman
4.5 / 5 (8) Feb 24, 2011
How is the dark matter postulated to exist to account for lensing any different than the dark matter postulated to exist to account for galaxy structure?

The lensing effects were observed way after DM was originally proposed to exist, so lensing is an independently observed effect which SUPPORTS the existing DM hypothesis.

That's how scientific theories gain currency:

1. Anomalous observation is made
2. Try to explain it with known physics
3. If 2) is not possible, propose possible alternative(s)
4. Try to verify alternative(s) or gather supporting evidence
5. If supporting evidence is found, look for more - you're likely on the right track.
6. Reject alternatives that DON'T work
7. Keep going until you discover the nature of the beast.

I've really said all I can say on the matter and so at the risk of repeating myself to no effect, I'm bowing out.
frajo
5 / 5 (2) Feb 25, 2011
But on the extra dimensions part, they're too tiny to detect,
Not really. In principle there's no obstacle to measure gravitation on scales less than 1 mm. Ingenious experimenters like Michelson & Morley are needed.
The LHC, too, could give some hints of extra-dimensions.
frajo
3.2 / 5 (6) Feb 25, 2011
Honestly, sometimes I wonder why I bother to post stuff if people are simply going to ignore it. How many times need I mention gravitational lensing maps?
You are entitled to your opinion. But it's not the only opinion.
There's no physical connection between the gravitational lensing phenomenon exhibited by galaxy clusters and the problem of fitting galactic rotation velocities to Newtonian dynamics. If you postulate that both phenomena have the same cause that's fine. But nobody is obliged to concur.
Most people are cautious and refrain from displaying a certainty which is not sufficiently backed by theory plus observations. They think "maybe there are DM particles, but maybe the known rules don't work out there".
It is not stupid to hesitate when things are not settled yet.
DavidMcC
4.8 / 5 (4) Feb 25, 2011
WIMPS have, as a previous poster pointed out, never been shown to exist. MOND, on the other hand, was admitted by its proposer to be an arbitrary add-on to Newton's second law, with no theoretical justification, only as a fudge to make theory fir data.
I see parallels here with both the centrifugal force, a term that would have to be inserted into the Newton's force equation for a rotating frame and, (in another law), with Einstein's cosmological constant (CC), originally proposed to make the universe something it isn't - static). I am not saying that every spiral galaxy is in a separately rotating space of its own, merely that MOND looks like a similar kind of fudge to cover for a phenomenon that cannot be explained in a single universe (or vacuum if you prefer).
DavidMcC
5 / 5 (1) Feb 25, 2011
WIMPS have, as a previous poster pointed out, never been shown to exist. MOND, on the other hand, was admitted by its proposer to be an arbitrary add-on to Newton's second law, with no theoretical justification, only as a fudge to make theory fir data, as is the case here.
I see parallels here with both the centrifugal force, a term that would have to be inserted into the Newton's force equation for a rotating frame and, (in another law), with Einstein's cosmological constant (CC), originally proposed to make the universe something it isn't - static). I am not saying that every spiral galaxy is in a separately rotating space of its own, merely that MOND looks like a similar kind of fudge to cover for a phenomenon that cannot be explained in a single universe (or vacuum if you prefer).
TabulaMentis
1.8 / 5 (5) Feb 25, 2011
We are dealing with two separate phenomena. The causes might not be identical.
Frajo makes a good point that scientists should be trying to figure out.
Pyle
3.4 / 5 (8) Feb 25, 2011
There's no physical connection between the gravitational lensing phenomenon exhibited by galaxy clusters and the problem of fitting galactic rotation velocities to Newtonian dynamics.

WHAT?!? Its the same field equations. Gravitational lensing DOES corroborate the dark matter plug. (I don't think it should be considered evidence though. Semantics...) The increased spacetime curvature caused by the missing dark matter would lead to both the rotational velocities and the lensing. This just means the dark matter hypothesis is consistent within GR. (Somebody look for a galaxy where we have rotation and lensing data.)
Moffat's MOG is a similarly consistent alternative solution that proposes a fifth force instead of the missing matter. (Last mention. I promise. Really good read though.)
PinkElephant
4.6 / 5 (8) Feb 25, 2011
@Pyle,
There have been more direct "indirect" detections of DM than just lensing maps indicating more mass around visible galaxies/clusters than is optically observed.

There have actually been observations of apparent separation of DM from OM, due to collisions of galaxies and galaxy clusters. For instance, look up "Bullet Cluster" and "MACS_J0025.4-1222". Here you have observational records of "mass" (inferred from gravitational lensing) that isn't visible, is spatially separated from visible mass, and apparently isn't subject to strong interactions during head-on cosmic collisions, unlike ordinary matter.

These observations are what, IMHO, puts the nail into the coffin of MOND and MOND-like theories. Like the article mentions, there's still a chance that on small (intra-galactic) scales gravity might still be non-Einsteinian to some extent. But on galactic and inter-galactic scales, DM is pretty much confirmed (even though we still don't know what exactly it is made of.)
DavidMcC
1 / 5 (1) Feb 26, 2011
Could it be that it is the rotation of the super-massive black hole at the centre of a spiral galaxy that keeps the stars from flying off at the edges, by "dragging space round with it"? Is it a strong enough effect, given that the mass of the BH is only a small proportion of the mass of the galaxy?
soulman
4.6 / 5 (9) Feb 26, 2011
Could it be that it is the rotation of the super-massive black hole at the centre of a spiral galaxy that keeps the stars from flying off at the edges, by "dragging space round with it"? Is it a strong enough effect, given that the mass of the BH is only a small proportion of the mass of the galaxy?

No. The galaxy as a whole, including its black hole, simply doesn't have the required mass to keep stars from flying off. The rotational aspect of the BH is also not relevant here (frame dragging is a very localized phenomenon, even for a BH).
DavidMcC
4.5 / 5 (2) Feb 26, 2011
Thanks, for that, soulman.
SteveL
5 / 5 (8) Feb 26, 2011
frajo: "Physics: Looking in a dark basement for a black cat which might not be there."


Oh, something is there, not a black cat, but assuredly "something" is there in the darkness. The real darkness is our lack of perception or understanding. We've only consistantly been at this physics for several hundred years, and I'm betting that in the not too distant future someone will be able to explain to us how to look at what we presently can't.

Our conundrum is that we just don't like not knowing - and that's not a bad thing. Between now and then there will be hypothesis and theories and a bit of stumbling, but that's OK because we will still keep banging away at our ignorance until we uncover the solutions we seek.
MorituriMax
4.4 / 5 (7) Feb 26, 2011
I agree with the posts here. I never believed in Dark matter/energy.

A lot of scientists are going to be feeling really foolish when those ideas are totally debunked. They really should have (and many may have) known better. Of course, this is opinion at this point. The facts will come out eventually.

Not to be blunt, but the fact that you think that what you believe matters at all in science makes you look as stupid as you think all those scientists look. If you had lived a few hundred years ago, you likely would have "believed" that the Sun burns coal to generate energy, and you wouldn't have even known that bacteria existed.
frajo
3.8 / 5 (4) Feb 26, 2011
Our conundrum is that we just don't like not knowing -
True. The most powerful motivator for human development.
and that's not a bad thing.
It is not a good thing either, historically speaking. For it gave and still gives rise not only to the scientific method but also to world views, ideologies, religions, superstitions and their pandora boxes of suffering.
ECOnservative
1.8 / 5 (5) Feb 26, 2011
For more background on MOND, see //www.americanscientist.org/issues/pub/dark-matter-heretic for an interview with Milgrom.

It's nice when something postulated far before observations matches near perfectly. Elegance favors truth (and frequently simplicity).
GuruShabu
2 / 5 (8) Feb 26, 2011
Dark matter and the infamous dark energy are the CO2 and the global warming of present science. They were invented to try to explain why the galaxies rotated faster than our gravitational theories predicted. And then all of a sudden they are in all papers and in all news (this is really bad!) inoculating the minds of lay people with this unproven and unlikely concept.
TabulaMentis
1 / 5 (4) Feb 26, 2011
It is not a good thing either, historically speaking. For it gave and still gives rise not only to the scientific method but also to world views, ideologies, religions, superstitions and their pandora boxes of suffering.
One of the Pandora Boxes will be World War Three about three and a half years after humans figure out how to read peoples minds, for those new energies humans will possess will be way too tempting for most to not use for evil means. Get ready, it is coming sooner than most think.
Pyle
3.5 / 5 (4) Feb 26, 2011
Pink Elephant:
Bullet Cluster... These observations are what, IMHO, puts the nail into the coffin of MOND and MOND-like theories.

Agreed. I think I have the same feeling for MOND. However, Moffat and Toth have fit MOG to the Bullet Cluster without free variables (as MOND would have to) or dark matter (as GR requires) arXiv:1005.2685v1

Search Moffat (J.W.) on arxiv and there are a couple of more recent papers and talks posted that you can get a sketch of his MOG theory. It seems to be very promising, postulating a fifth force rather than dark matter. I like it because it does away with singularities and some other nastiness. I am curious to see if it can get rid of time tunnels, vis a vis Godel universes as well, but haven't seen anything on it yet.
Pyle
3.3 / 5 (4) Feb 26, 2011
Finally, per Moffat in his book Reinventing Gravity, the Abell 520 merging clusters paints a picture of DM that seems to be contradictory to the Bullet Cluster. see Mahdavi et al arXiv:0706.3048v1 Moffat and Toth have explained it with MOG using only normal baryon matter.

I also ran across a couple of ideas to make MOND a full fledged theory that were interesting but not fully developed yet. These might be alternatives, but so far MOND still needs DM in certain existing observations, bullet et al.
Parsec
4.3 / 5 (3) Feb 27, 2011
It is quite conceivable that both MOND and dark matter exist. DM is simply congregations of particles currently unknown, while Newton's gravity is modified at very large scales.
frajo
3 / 5 (2) Feb 27, 2011
However, Moffat and Toth have fit MOG to the Bullet Cluster without free variables (as MOND would have to) or dark matter (as GR requires) arXiv:1005.2685v1

Search Moffat (J.W.) on arxiv and there are a couple of more recent papers and talks posted that you can get a sketch of his MOG theory. It seems to be very promising, postulating a fifth force rather than dark matter. I like it because it does away with singularities and some other nastiness.
I had a look into some arXiv papers dealing with MOG leaving me quite impressed. They even have an option for a cyclic cosmology (arXiv:1011.5174). "Reinventing Gravity" is ordered.
SteveL
not rated yet Feb 27, 2011
and that's not a bad thing.
It is not a good thing either, historically speaking. For it gave and still gives rise not only to the scientific method but also to world views, ideologies, religions, superstitions and their pandora boxes of suffering.


Pandora boxes of suffering can come from many sources, not just our ignorance. Brilliant people can still do any of a vast number of incredibly stupid things, even when they know better. But still we continue, hopefully progressing, despite our flaws. Creating and building require far more effort than destroying, so the fact that we've gotten this far gives me hope.
Pyle
2.7 / 5 (3) Feb 27, 2011
It is quite conceivable that both MOND and dark matter exist. DM is simply congregations of particles currently unknown, while Newton's gravity is modified at very large scales.

Parsec, you are 100% on, but I think you twist the issue. I don't think anybody is saying we can see everything out there. Look to the recent surveys and the increase in number of dwarf stars projected.
What I think is in question is the existence of exotic dark matter, collisionless etc., that represents five times the mass of baryonic matter in the universe.
TabulaMentis
1 / 5 (4) Feb 27, 2011
Pandora boxes of suffering can come from many sources, not just our ignorance. Brilliant people can still do any of a vast number of incredibly stupid things, even when they know better. But still we continue, hopefully progressing, despite our flaws. Creating and building require far more effort than destroying, so the fact that we've gotten this far gives me hope.
What concerns me is whose moral standards am I going to have to live by once the perverts in the government and media have control of my mind. I am sure when that day arrives and people start witnessing for themselves what is happening that they too will become paranoid to the point of civil war braking out throughout the entire planet. Good luck with that hope thing because you are going to need lots of it. Be prepared, it is not going to be pretty.
Tachyon8491
2.5 / 5 (8) Feb 27, 2011
MOND exceeds epicycle fantasy in its artificial synthesis. Dark Matter is an unavoidable implication of empirical observation and still fits the cosmogonic model best. There may well be better, future finetuning of the gravity-model, just as D. Bohm added the Quantum Potential term to the Schrodinger wave equation, but MOND appears all of a synthetic solution.

FV
Mercury_01
4 / 5 (3) Feb 28, 2011


Dark Matter doesn't predict ANYTHING.

Dark Matter and Dark Energy are constantly being used as an arbitrary PATCH to explain why mainstream theories FAIL to predict galactic and intergalactic motion.


Dark matter theory predicts exactly where every measurable galaxy will be tomorrow morning at eight. plus it vibes well with M theory. If you want to get your tightey whiteys in a bunch, talk shit about dark energy instead.
frajo
2 / 5 (1) Feb 28, 2011
Dark matter theory predicts exactly where every measurable galaxy will be tomorrow morning at eight.
You don't need any DM to predict that.
But I'd like to see a DM theory explanation for Abell 520.
And a cosmology simulation based on DM theory which doesn't fail to yield the observed dwarf galaxy distribution by orders of magnitude.

plus it vibes well with M theory.
This is equally true for DM-free cosmologies. (See Ekpyrotic/Cyclic model of Steinhardt/Turok.)
DavidMcC
1 / 5 (2) Feb 28, 2011
What we know as "THE Big Bang" was, in reality, just a cheap, little

second-hand, CONTAMINATED bang. The evidence? Lots of little hints from

cosmology, plus the so-called Anthropic Principle (strong form).
What are the "hints"? The most signifcant one is the evident imbalance between matter and anti-matter in the very early universe, leading to galaxies, stars, and, of course, us. Another is the small amount of helium and trace of lithium. If our BB was "pure", ie came from "nothing", I don't see how this could be the direct result. It looks to me as if our BB was the result of the gravitational collapse of a small proportion of the original "stuff" after random fluctuations were acted on by gravity. There must have been other such collapsed bodies, with randomly different imbalances.
DavidMcC
3.5 / 5 (2) Feb 28, 2011
IMO, the biggest problem with cosmology at the moment is the rut it's in that comes from the general concensus that cosmology is particle physics and ONLY particle physics. This closes minds to the problem that the nature of the space that supports the existence of those particles is simply not addressed, and is left to the guesswork of pure mathematicians, with their Kalabi-Yau spaces, etc., trying to bypass any physical concepts.
Ethelred
3.7 / 5 (3) Feb 28, 2011
plus the so-called Anthropic Principle (strong form).
The Universe Must HAVE HUMANS to exist, which is arrogant to the point being ludicrous.

The most signifcant one is the evident imbalance between matter and anti-matter in the very early universe
We don't have a full answer but we do have two sources of CP violation so far. Not enough to explain the present balance but it does show that the Universe has a preference for matter.

Another is the small amount of helium and trace of lithium.
That one is understood.

ttp://en.wikipedia.org/wiki/Nucleosynthesis#Big_Bang_nucleosynthesis

If our BB was "pure", ie came from "nothing", I don't see how this could be the direct result.
The percentages are dependent on how fast the Universe cooled down. Longer cooling times would have resulted in more lithium and helium.

There must have been other such collapsed bodies, with randomly different imbalances.
That would show as variations in the CMBR.

Ethelred
DavidMcC
1 / 5 (1) Feb 28, 2011
Ethelred, you completely misunderstood my reference to the "Anthropic principle" - in two ways:
(a), it actually refers to the fact that the universe APPEARS to have been "fine-tuned" for life (ie for a complex biochemistry to be possible), and (b) you seem unaware that there is a natural explanation of that appearance (of the "strong anthropic principle"), along similar lines to the "weak anthropic principle", which postulates that many planets in this universe allow observers on at least one. Thus the solution to the strong antropic principle is simly many universes.
You completely misunderstood the last point, because I was referring to collapsed bodies in a universe that gave birth to this one, not this one itself.
yyz
5 / 5 (6) Feb 28, 2011
@frajo

"I'd like to see a DM theory explanation for Abell 520"

The 2007 paper by Mahdavi et al found an apparent massive dark matter 'core' in A520 that did not coincide with the presence of luminous matter (galaxies), which would be a problem for the LCDM paradigm.

A more extensive study of A520 (Girardi et al 2008) found that the cluster is forming at the confluence of 3(!) LSS filaments. It appears that one of these filaments is seen projected along the line of sight to the cluster and is partially responsible for what is observed here.

This possibility of a projected filament is even mentioned in the earlier paper by Mahdavi(Sec 4.2). Given this scenario, it appears there is no 'massive dark core' or inconsistency with the current thinking on CDM exhibited by A520.

2007 Mahdavi paper: htp://arxiv.org/PS_cache/arxiv/pdf/0706/0706.3048v1.pdf

2008 Girardi paper: htp://arxiv.org/PS_cache/arxiv/pdf/0809/0809.3139v1.pdf

(see esp. Secs 5.5 & 6)

Ethelred
3.7 / 5 (3) Feb 28, 2011
(a), it actually refers to the fact that the universe APPEARS to have been "fine-tuned" for life
Perhaps you should have made yourself more clear. You did say STRONG.

ttp://en.wikipedia.org/wiki/Anthropic_principle

The Strong Anthropic principle as explained by Barrow and Tipler (see Variants) states that this is all the case because conscious life, in some sense, needed to exist.
I think the Strong Anthropic Principle is crap. Don't use the term STRONG if you don't mean it.

(a), it actually refers to the fact that the universe APPEARS to have been "fine-tuned" for life (
That is backasswards. WE, as is all life, are tuned, by natural selection for the Universe we live in.

(b) you seem unaware that there is a natural explanation of that appearance
Uhn. No. I am aware of why we are tuned for the Universe. Perhaps YOU are not aware of what the STRONG version is about. It claims that intelligent life MUST exist for the Universe to exist.

More
Ethelred
3.7 / 5 (3) Feb 28, 2011
which postulates that many planets in this universe allow observers on at least one
No. It says since life exists the laws of the Universe must allow it.

Thus the solution to the strong antropic principle is simly many universes
That is NOT the Strong version. In the Strong version NO universe can exist without INTELLIGENT life.

You completely misunderstood the last point
No.

I was referring to collapsed bodies in a universe that gave birth to this one, not this one itself.
I understood that just fine. It is why I said there would be indications of that in the CMBR.

We don't appear to live in a cyclic Universe. The rate of expansion appears to be accelerating not decelarating. Even if it isn't accelerating we still don't see enough mass to close the Universe. Even with the idea that the negative energy of gravity and the positive energy of matter cancel each other out for a net energy of zero you still get a Universe that will not collapse.

Ethelred
SteveL
5 / 5 (1) Feb 28, 2011
Pandora boxes of suffering can come from many sources, not just our ignorance. Brilliant people can still do any of a vast number of incredibly stupid things, even when they know better. But still we continue, hopefully progressing, despite our flaws. Creating and building require far more effort than destroying, so the fact that we've gotten this far gives me hope.
What concerns me is whose moral standards am I going to have to live by once the perverts in the government and media have control of my mind. I am sure when that day arrives and people start witnessing for themselves what is happening that they too will become paranoid to the point of civil war braking out throughout the entire planet. Good luck with that hope thing because you are going to need lots of it. Be prepared, it is not going to be pretty.


Why would you give up control of your mind? Seems to me the greatest danger is if you actually do capitulate. It's your mind, own it.
TabulaMentis
1 / 5 (6) Feb 28, 2011
Why would you give up control of your mind? Seems to me the greatest danger is if you actually do capitulate. It's your mind, own it.
Wow. I thought what I said was quite clear as to what people (perverts) in the future will be able to do, like read peoples' minds. If one can read something, then it should be possible to program (brainwash) something. Let's compare what I am talking about in the future to today's computer technology like: worms, viruses, drive-by downloads/uploads and so forth. How are you going to prevent someone (pervert/jerk) in the future with a device from instructing your mind to jump off a bridge, kill your wife or rape your kids? Tell me what you are going to do to prevent it from happening? Sit back and think about for a few years and then let me know. Maybe it will be too late by then.
DavidMcC
not rated yet Mar 01, 2011
Ethelred, you are quoting different versions of the strong and weak principles to suit you. If you read the Wiki page you linked, it lists sensible versions of both the strong and the weak principles. Of these, only the Carter versions are sensible, and I tend to ignore all the other, stupid versions. I think the Carter versionmof the strong principle should be addressed by cosmology, in the form of a multiverse.
The other issue you need to think about is that evolution to "fit the puddle" can't happen unless there is abiogenesis first.
unknownorgin
1 / 5 (2) Mar 01, 2011
Time passes slower for an object in motion, also time slows down in a gravitational field. The velocity, time, gravity connection is there so spinning objects have more gravitational pull than the sum of thier mass.
There is no dark matter.
Skeptic_Heretic
5 / 5 (1) Mar 01, 2011
Wow. I thought what I said was quite clear as to what people in the future will be able to do, like read peoples' minds.
With enough objective observation, one can determine your motivation and actions before you conceive of them. Everything is predictable given enough information.
The velocity, time, gravity connection is there so spinning objects have more gravitational pull than the sum of thier mass.
Absolutely not.
DavidMcC
5 / 5 (1) Mar 02, 2011
The energy of spin represents an effective mass, m = (spin energy)/c-squared. To that extent, spin increases gravitational pull, presumably.
TabulaMentis
1 / 5 (2) Mar 02, 2011
With enough objective observation, one can determine your motivation and actions before you conceive of them. Everything is predictable given enough information.
I am not a believer in the notion that God can predict the future with 100% accuracy. You are beginning to sound religious Skeptic Heretic.
OdinsAcolyte
1 / 5 (1) Mar 02, 2011
Nothing still explains what gravity is. Does it exist independently of matter? No. Is there such a thing as Dark Matter? perhaps. Is string theory correct? I doubt it. We still do not know enough to say much do we? It is what it is. Will the Universe expend until it suffers the uniformity of heat death or contract and expand again? Probably neither. I shall evolve. Just like us.
Ethelred
3 / 5 (2) Mar 03, 2011
Ethelred, you are quoting different versions of the strong and weak principles to suit you.
I am using the usual versions.

it lists sensible versions of both the strong and the weak principles.
There are no sensible versions of the Strong principle.

Of these, only the Carter versions are sensible, and I tend to ignore all the other, stupid versions.
The Carter version of the the Strong isn't the Strong Anthropic principle it is just the Weak Anthropic Principle spread over a multi-verse. There is no need for a Strong and Weak version IF the strong version is the same as the weak and that is what you are saying.

The other issue you need to think about is that evolution to "fit the puddle" can't happen unless there is abiogenesis first.
Really? I didn't know that. I must have been a Creationist and didn't know it.

I was already fully aware of that. I only point that out to Creationist no more than 3 or 4 times a month. Or is that a week.

Ethelred

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