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Well, they weren't, not really sure how else to put that Isaac Send a noteboard - 10/05/2011 03:19:57 AM
We haven't completely totally absolutely ruled out more mundane options, and frankly there's been a lot of effort to to come up with those, they just tend to suck balls, if you're under the impression most physicists approach DM with a disposition to hoping its true I'd say that's backwards.

That's only my impression and I don't claim authority on the subject, so I could well be wrong. I'm trying not to speculate on potential causes should my impression prove accurate. I don't want to criticize scientists on the one hand for pressing radical revisions of conventional wisdom to gain a reputation by proving exotic dark matter exists, and on the other for supporting dark matter solely because it's the current conventional wisdom.


Again, while physics is a field like all others possessing human beings with all their little idiosyncrasies, there is not some cult-like push for WIMPs to be real. We have a lot of mass, or we're 99% certain we do, we've looked for every conceivable 'mundane' source we can find, so we posit some sort of thing which could account for the mass and remain undetected to our previous - and ongoing and increasingly accurate - search methods. Such a particle would, presumably, not interact much and be pretty massive, some sort of 'weakly interacting massive particle' or something like that. Or maybe some mundane object that hangs around on the outskirts where it's hard to see, in the Galactic Halo, and compact too, making it harder to see, some sort of massive, compact, halo object. So we look for the MACHOs, and we don't see them, or rather we do see them, that's the problem, we see them so we know we can see them and we don't see enough of them and there's no reason to think we're not seeing an even spread, so we say "It is very unlikely the Dark Matter is primarily MACHOs, what else is left? Oh, those WIMPs, we haven't ruled those out yet" and so on.

It can take time, but doesn't have to take much; the neutrinos discovery took 25 years after postulation, but the quark only took four. But what I meant by the reference to neutrinos is that it's one thing to find a single predicted subatomic particle whose unique properties make it unaffected by electromagnetism and quite another to posit a whole new class of matter composing macroscopic objects five times the mass of normal matter. I'm not saying it doesn't exist or shouldn't be researched, I just don't want to rush to definitively say it does exist.


Yeah, great example, it took us decades to find neutrinos because the interact weakly... quarks interact pretty strongly, so strongly we call their interactive force the Strong Force... because we're lazy about naming things. For us to find something, it must interact with something else and do so so that we know it interacted, as you might imagine, this is much easier to do when there are lots of potential interactions and they occur strongly. You know the sort of measures that were needed to find neutrinos, and you get hit by trillions of them a second, these particles are harder to find and are much less common here.

I agree that most matter meets the broad definition of dark matter; in a sense, that's my point: If we're simply talking about non-emitting non-relective normal matter, matter we can see is probably more rare than normal matter we can't, which is to say, neither of them is very exotic at all. Ultimately that was my real point in commenting initially: "Dark matter" is a phrase whose meaning seems to vary with whom you ask, and the evidence for the exotic variety is still inconclusive, so I don't want to count my chickens before they're hatched. I'm probably a little biased in favor of dark matter being a particular type of normal matter because I perceive a bias the other way.


I almost feel like you're objecting because you dislike the words 'dark' or 'exotic'. Their just words, for God's Sake we named two quarks "Strange" and "Charm" because the first strange quark particle had a 'strangely long life' and nobody even knows about charm, and we used to cal the other two truth and beauty but it was a bit too eyerolling even for us. All you're telling me is that you think you might be biased on the subject because you think we are. But the problem is you present nothing indicating we are, and well, this is physics, we don't snap at people for saying they think we might be wrong, that kind of ego and wounded pride aren't really common in the field where profs generally yell at students for not catching their mistakes. I can't refute your 'vibes' either. We call the stuff exotic because we don't know what the stuff is only that it is not normal... of course its probably the most common thing in the universe so I guess whatever it is normal, and we've eliminated a lot of candidates. This is normal scientific procedure, if we're not moving fast enough for you, well I'm sorry, there aren't a lot of physicists and most of us don't study this stuff, we basically have to spread ourselves out to cover ever field of science that hasn't split off into some sub-field, and the kinds of experiments we have to do to find this stuff usually requires nation state levels of money and manpower. Every time we have to come up with a whole new plan and experiment, its like if I told you I had written 'Bob' on a large number of 1 dollar bills, in invisible ink that can only be seen in one small range of light frequencies but which ones I won't tell you, and that I wrote Bob in only 6 sizes and produced and equal quantity of each size, and that I used exactly 1 kilogram of ink, and you had to find them without every touching them yourself, so you decide the best way to do this is is to set up monitors near walmart cash registers looking at different frequencies, hoping the detectors come back with a hit showing an abnormal reflection of light in a given spectrum consistent with the location and general duration of a cash exchange, once you get one, you can make a decent guess what frequency its one and increase the number of detectors for that frequency and their sensitivity, and before you might be able to determine that these 'flash events' occur in six discreet amounts, and from that you may be able to ferret out the average thickness of the ink, then determine how much each additional bill weighs based on the velocity of the moving patch of reflection and how the increased mass changes the drag on the bills as they pass through air. And from that, at last, you can extrapolate the mass of ink used to write each of the six sizes of "Bob" and determine how many bills he wrote on. Of course simultaneously someone may have run a model trying to figure out what percentage of $1 pass through Walmarts and compare it to the number of reflected incidents, and someone else might come by and show that Strip Clubs have an even higher flash event duration and give better if smaller amounts of data, and someone else might come by and show in all probability the ink decays and that not only has much of the 'noise' we thought we saw actually been real events but that our figures have also failed to account for the number of bills that have been soaked in water and no longer flash at all. Not an easy process, finding quarks is like that, finding neutrinos would be like trying to detect those flash events by monitoring the clothing people are wearing when they exit the store to see if they faded more than in a place where more transactions are carried out by electronic means, and if that fading of color indicates flash events took place, and that it only works on wool clothing dyed red, and can only be detected on clothing that has non-red colors as well to compare to. Finding WIMPS is like trying to determine fading from increased clothing sales amongst cash register clerks. I think decades of scientific discovery may have given you a warped viewpoint on how hard this sort of thing actually is.
The intuitive mind is a sacred gift and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift.
- Albert Einstein

King of Cairhien 20-7-2
Chancellor of the Landsraad, Archduke of Is'Mod
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Exciting video about the universe - 28/04/2011 10:14:55 AM 1091 Views
Cool, and true *NM* - 28/04/2011 11:46:29 AM 332 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 817 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 750 Views
I'm aware of the Bullet Cluster, though admittedly not much more than that. - 29/04/2011 01:52:49 AM 680 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 29/04/2011 02:56:32 AM 793 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 30/04/2011 05:02:49 PM 749 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 30/04/2011 08:56:35 PM 619 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 02/05/2011 01:28:30 AM 653 Views
Re: I'm aware of the Bullet Cluster, though admittedly not much more than that. - 04/05/2011 04:18:18 AM 758 Views
There's such a thing as knowing when you're licked, and I believe I am. - 07/05/2011 02:04:53 AM 829 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 673 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 618 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 707 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 629 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 705 Views
The Pati-Salam model was the one I had in mind. - 24/05/2011 10:34:04 PM 648 Views
Re: The Pati-Salam model was the one I had in mind. - 24/05/2011 11:08:01 PM 856 Views
Re: The Pati-Salam model was the one I had in mind. - 25/05/2011 01:27:10 AM 667 Views
Re: The Pati-Salam model was the one I had in mind. - 31/05/2011 09:16:18 AM 737 Views
Also, re: lensing from ordinary matter: - 29/04/2011 05:18:47 AM 681 Views
This seems like another example of what confuses the issue. - 30/04/2011 05:25:04 PM 800 Views
Re: This seems like another example of what confuses the issue. - 30/04/2011 08:56:40 PM 772 Views
That discussion seems to reduce to "as little new and exotic physics as possible". - 02/05/2011 01:29:03 AM 764 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 999 Views
Seems to happen to me a lot; sorry. - 29/04/2011 12:56:14 AM 698 Views
None of this reflects on the actual facts of dark matter. - 29/04/2011 01:32:52 AM 664 Views
I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 30/04/2011 04:30:28 PM 780 Views
Re: I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 30/04/2011 08:56:44 PM 614 Views
Re: I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 02/05/2011 01:28:58 AM 1131 Views
Re: I concede my grasp (or grope) is a somewhat superficial laymans, yes. - 04/05/2011 04:18:27 AM 658 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 850 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 775 Views
Might help if you clarified where your skepticism is at - 29/04/2011 02:32:07 AM 636 Views
Potentially either, or a combination of the two. - 30/04/2011 02:36:50 PM 700 Views
It's hard to discuss without knowing your objections a bit more clearly - 30/04/2011 04:58:03 PM 615 Views
My primary objection is that alternatives to dark matter seem to have been ruled out prematurely. - 02/05/2011 01:29:14 AM 752 Views
Well, they weren't, not really sure how else to put that - 10/05/2011 03:19:57 AM 789 Views
Alright then, objection withdrawn (cautious skepticism intact). - 14/05/2011 05:34:17 AM 907 Views

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