Is it good reading? Lisa Randall -Dark Matter and Dinosaurs

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Re: Is it good reading? Lisa Randall -Dark Matter and Dinos

Postby Ormond on January 25th, 2016, 7:32 pm 

Faith is such a shaky foundation for any intellectual endeavor.


Exactly. Which is why atheism must be rejected, it depends on faith, just like theism.

Your assertions #1 & #2 are really quite independent of (a) DM and (b) religion,


Yes, agreed, they are, which is why we shouldn't discuss them in this thread. I only mentioned them in a desperate attempt to engage you before you have to go. :-)

but they do have the sniff of kneejerk dismissiveness of authority but have none of the scent of a comparably nuanced position. Dost thou have some overarching axe to grind? Is this nothing more than anti-intellectualism posing as wisdom?


Look my new friend, meant sincerely, none of this works on me. It just doesn't. Spare yourself some typing.

Engage the assertions directly if you wish, or run from them as most others do. I'm ok with it either way, and really only wish to engage on those topics in which we both have a real interest.
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Re: Worth a Video!

Postby Faradave on January 25th, 2016, 8:06 pm 

Lincoln wrote:Fact: DM >>DOES NOT<< experience the weak nuclear interaction.

I really enjoy your Fermi Lab videos, as I'm sure many do. This statement seems new enough and important enough to bring to the public, especially in light of the WIMP acronym. I hope you'll consider it.

I still think it's premature to rule out (as DM) matter that's dark and happens to interact weakly (i.e. neutrinos). But I'm willing to learn more. Sterile WIMPs (or whatever they should be called) may be a big part of the answer.

Lincoln wrote:Fact: DM does not emit electromagnetic radiation and therefore does not lose energy as it orbits a black hole.

That's a nice nugget. I'm going to enjoy thinking about that for some time. Thanks!

Off the top of my head:
As ordinary particles would seem preferentially bound to energy loosing orbits (at least electrons and ions, not sure if this applies to neutrons or larger neutral composite particles), that means DM is less bound to neighboring gravitational bodies in the vicinity of a black hole. That would seem to make DM freer than ordinary matter to wander (diffuse?) into black holes. So I'm not sure about the percentage entering black holes.

Lincoln wrote:Fact: DM is very rare inside a star and most of the mass of black holes comes from the stellar implosion and not from accretion

Yes. I must agree, for typical black holes. That was naive of me. However, once the degeneracy threshold of a neutron star is passed, it would seem the collapse would lead to a fundamentally neutral result. If you're of a mind that black holes don't interact weakly, they would all-the-more fit the DM category, as you describe it.

Remember, I was addressing extreme examples of DM. I'm not purporting that black holes or neutrinos explain the majority of gravitational evidence for DM.

Lincoln wrote:OP of this thread? The hypothesis of strongly self-interacting DM is a pretty new and broad idea.

Agreed. Especially in light of these 2015 statements:

"dark matter interacts with itself even less than previously thought... These latest results rule out interactions that create a strong frictional force, causing dark matter to slow down during collisions."
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Re: Is it good reading? Lisa Randall -Dark Matter and Dinos

Postby Lincoln on January 26th, 2016, 12:56 am 

Ormond,

I disagree with you 100% on how you characterize atheism. There is no faith involved. Atheism is the default. I assume the existence of nothing and then build a hypothesis from logic and data. For instance, I do not need to defend against hypotheses of unicorns, fairies, or rational Republican candidates in 2016. If somebody wants to claim such things exist, the onus is on them. I don't need to hypothesize an Ormond exists. There must be some evidence that leads to a hypothesis.

That hypothesis, once advanced, is subject to testing both internal or empirical. Thus if someone postulates some religious thing or another, then there are two conditions in which that hypothesis can exist. The first is an unchallenged state, which isn't much of a condition to be in. The second is a challenged state that has not yet been disproven. That's as good as it gets. Thus an atheism has nothing to prove and bases nothing on faith. It is the default position and the entire responsibility is on those who claim otherwise.

Regarding the axe to grind thing, I don't fully understand your admonishment, but given the three quasi-unrelated topics, it smells like many discussions I've been in before. This may be wrong, but my Spidey sense is tingling.

Regarding your 2 assertions, failure to engage is not running from them. Don't elevate them to some high and scary level. They're not >>THAT<< insightful...more along the lines of an interesting diversion.

You will no doubt choose to disagree with my observation, but it appears that you feel that you have a superior insight into the world that is lost on the less enlightened, where the less enlightened include some very smart people. That's not entirely unusual, but those conversations rarely go well. It may well be that your nominal opponents have already considered the position and found it wanting. Further, long experience suggests that the conversation will be unproductive, therefore it's better to not waste the time. Call it cowardice or call it experience.
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Re: Is it good reading? Lisa Randall -Dark Matter and Dinos

Postby Lincoln on January 26th, 2016, 1:00 am 

Faradave,

I promise you on the weak force. WIMPs might still experience the weak force, but only if other, undiscovered particles exist. I could show you the plots, but I expect that they might not convey the proper message to you.

Other, even-weaker, forces, remain possible.

I'll have to deal with your other comments later. However, I can only say at the moment that your conjectures have been tested and definitively falsified.

This not to say that we know what dark matter >>IS<<, however we know tons and tons and tons of what it >>ISN'T<<. Unfortunately, your conjectures are all on the "isn't" list.
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Re: Related Links

Postby Faradave on January 29th, 2016, 2:58 am 

For those who may not be aware Don Lincoln has done an excellent, accessible video series for Fermilab and there is a collection of them in this SPCF thread.

Here are articles relating to DM and black holes and a video.
Dark Matter Guides Growth of Black Holes
Black Holes as DM Labs (by concentrating it).

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