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There's such a thing as knowing when you're licked, and I believe I am. Joel Send a noteboard - 07/05/2011 02:04:53 AM
Perhaps so, but the evidence for any one explanation (or group of explanations) still seems inconclusive.

Again, that's because you have an overly-limited view of the evidence.

Perhaps so. It doesn't sound like a case of ruling out one thing ruling in another, not when we still await direct evidence of dark matter.
An analogy to other types of known normal matter doesn't really help the cause of exotic dark matter. You're essentially listing other explanations for missing mass that require no exotic dark matter.


No, because those particles either have too little mass or are not stable, which precludes them from being dark matter candidates. The point is that particles which don't interact electromagnetically are not unknown.

Which means that in itself represents nothing exotic; we have direct evidence of it. What is now sought is very much unknown.
Ultimately, yes, and if dark matter and/or dark energy are invalid concepts then those ardently contending they're the only possible explanations and pursuing proof of same today will be much chagrined by tomorrows scientists exposing their errors. If that's how things develop, however, I'd prefer the process take decades rather than centuries, and the more inertia an erroneous theory has within the community the more evidence it will take to overcome it.

I think the suggestion that debunking a scientific hypothesis in the modern era could take centuries is ludicrous and without any support from recent history, taking into account the major progress in science since the scientific revolution.

Maybe not centuries given the rate at which things occur today (though the first team to detect a neutrino only got a Nobel Prize for it a half century later). Blind alleys and group think remain a valid concern though, one that's more serious rather than less as theories advance. Dusting off terms like "quintessence" for dark energy doesn't exactly reassure me there. Bottomline is that any time people become so committed to a theory that they cease questioning whether it could have a fundamental flaw all the review and experimentation in the world won't help them; when the evidence conflicts with an inviolable principle the search begins, not for a more accurate principle, but for a way to reconcile the evidence with the flawed the theory. That process will last as long as a community is willing to pursue it, and is less a function of research than of the theorys social inertia. If you say that's not happening I'll accept that since you're obviously in a better position to say so, but modern science hasn't made it impossible, and the idea it has is another example of the kind of unassailable certainty that makes me nervous.
That's fair enough, provided we don't inadvertently allow it become an excuse for never finding direct evidence. Otherwise there's no difference between dismissing the lack of direct evidence for dark matter and dismissing the lack of direct evidence for MACHOs; it's just a question of which theory unsupported by direct evidence one prefers.

As we're only in the beginning stages of direct detection experiments for dark matter, that is not yet a scenario which merits serious concern.

Fair enough; I'll wait and see, but the longer I wait the more I'll worry we're on the wrong track, especially if the only idea frustrated searches produce is "look HARDER!" ;)
I don't think it's flimsy, as such, but I do think it inconclusive.

Theoretical estimates of normal dark matter could be off.

Less of it could lie in the immediate vicinity of lensed objects but more along the complete path between us and them.

The image itself could be distorted if the lensing mass is so close it strongly affects parts of the background but others little or none.

Those are just the most obvious solutions occurring to one layman, acknowleding that all may be untenable. Regardless, the basic principle that experiments and observation should seek new theories and test existing ones rather than simply to prove existing ones remains valid. An anomaly alerted us to a problem, but just because a solution that may be tenable was found doesn't mean we should just set out to prove that solution and cease bothering to look for one that fits the evidence better, particularly if one exists that both fits the evidence better AND is simpler.

An anomaly alerted us to the problem and many, many observations confirmed the problem.

Proposing solutions without having a full understanding of the situation and evidence is generally a futile exercise.

Interesting comment; do you think someone has a FULL understanding of the situation and evidence, or that all proposed solutions are futile? ;)
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Exciting video about the universe - 28/04/2011 10:14:55 AM 1042 Views
Cool, and true *NM* - 28/04/2011 11:46:29 AM 311 Views
I still think dark matter's just non-luminous matter without a convenient light source to reflect. - 28/04/2011 10:34:21 PM 778 Views
We've just about ruled out the idea that dark matter is just non-luminous "ordinary" matter. - 28/04/2011 11:44:34 PM 707 Views
I'm aware of the Bullet Cluster, though admittedly not much more than that. - 29/04/2011 01:52:49 AM 641 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 29/04/2011 02:56:32 AM 746 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 30/04/2011 05:02:49 PM 707 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 30/04/2011 08:56:35 PM 579 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 02/05/2011 01:28:30 AM 616 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 04/05/2011 04:18:18 AM 714 Views
There's such a thing as knowing when you're licked, and I believe I am. - 07/05/2011 02:04:53 AM 790 Views
Re: There's such a thing as knowing when you're licked, and I believe I am. - 09/05/2011 11:28:48 PM 627 Views
Re: There's such a thing as knowing when you're licked, and I believe I am. - 14/05/2011 05:36:45 AM 573 Views
Re: There's such a thing as knowing when you're licked, and I believe I am. - 17/05/2011 02:09:40 AM 665 Views
Re: There's such a thing as knowing when you're licked, and I believe I am. - 19/05/2011 04:55:21 AM 587 Views
Re: There's such a thing as knowing when you're licked, and I believe I am. - 24/05/2011 09:32:27 PM 662 Views
The Pati-Salam model was the one I had in mind. - 24/05/2011 10:34:04 PM 607 Views
Re: The Pati-Salam model was the one I had in mind. - 24/05/2011 11:08:01 PM 812 Views
Re: The Pati-Salam model was the one I had in mind. - 25/05/2011 01:27:10 AM 624 Views
Re: The Pati-Salam model was the one I had in mind. - 31/05/2011 09:16:18 AM 693 Views
Also, re: lensing from ordinary matter: - 29/04/2011 05:18:47 AM 633 Views
This seems like another example of what confuses the issue. - 30/04/2011 05:25:04 PM 723 Views
Re: This seems like another example of what confuses the issue. - 30/04/2011 08:56:40 PM 731 Views
That discussion seems to reduce to "as little new and exotic physics as possible". - 02/05/2011 01:29:03 AM 729 Views
Re: I still think... (apparently, there is a 100 character limit on subjects, and yours was 99) - 28/04/2011 11:57:15 PM 945 Views
Seems to happen to me a lot; sorry. - 29/04/2011 12:56:14 AM 651 Views
None of this reflects on the actual facts of dark matter. - 29/04/2011 01:32:52 AM 619 Views
I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 30/04/2011 04:30:28 PM 745 Views
Re: I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 30/04/2011 08:56:44 PM 577 Views
Re: I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 02/05/2011 01:28:58 AM 1089 Views
Re: I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 04/05/2011 04:18:27 AM 619 Views
I don't object to changing my mind, but can take more convincing than I really should. - 07/05/2011 02:05:09 AM 810 Views
Re: I don't object to changing my mind, but can take more convincing than I really should. - 09/05/2011 11:32:17 PM 732 Views

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