Dark matter seems like a misunderstood component of gravity. The current explanations just seem ridiculous.
Modification of gravity has been found wanting. See e.g., the bullet cluster, https://en.wikipedia.org/wiki/Bullet_Cluster
Earth Might Have Hairy Dark Matter
31–40 of 118 posts
Re: Earth Might Have Hairy Dark Matter
#32ooooo
Re: Earth Might Have Hairy Dark Matter
#33The edge of human understanding of the universe is a vague and scary place. When we dug deep below the atom level everything we took for granted fell apart. We had to invent an entirely new model of physics to make sense of our observations, which is complex and counter-intuitive (quantum mechanics) Would it be reasonable to assume that the same applies at the opposite end of the spectrum: from the sub-atomic to the…
Possible! There certainly is a lot that feels inelegant in the dominant model, and nobody has yet proposed a reason that so much of the universe would be so oddly invisible to us. But (as I just noted in some detail in a different comment here) the "Lambda-CDM" model of a universe evolving in the presence of a cosmological constant and cold dark matter has proven to be quite remarkably consistent under a wide variety…
> nobody has yet proposed a reason that so much of the universe would be so oddly invisible to us.
Whilst I don't claim to have an answer to this question, I still wouldn't call it "odd".
We know of four fundamental forces (strong, weak, electromagnetic and gravitational) and we know that some particles are unaffected by some of these; e.g. leptons don't feel the strong force and neutrinos don't feel the electromagnetic force.
I would say the odd part is our assumption that matter should be visible (AKA electromagnetically interacting).
(Note: I'm only talking about dark matter here; dark energy is odd ;) )
Re: Earth Might Have Hairy Dark Matter
#34Earlier quoted context omitted.
As I understand, we can detect them through their gravitational effects and not much else. If we fully account for the pulls of all the non-dark bodies in the vicinity (Earth, Sun, Moon) and then manage to measure an anomalous gravitational pull (say on a mass connected to an extremely fine sensor) that changes with the motion of the measuring apparatus, that (I think) ought to do it. Disclaimer: not physicist.
actually, there is something that it is not really understood: the 5.9 years period of gravitational constant variation. [1]. Maybe the Earth is passing through such a filament? [1] http://phys.org/news/2015-04-gravitational-constant-vary.htm...
Interesting! But... it's been 15 years since my last university level physics course, but those error bars in the plot doesn't exactly lend lot of confidence to the idea of a periodic pattern?
Re: Earth Might Have Hairy Dark Matter
#35This seems like something straight out of SciFi. Dark matter actually forming invisible rods that go through the Earth? Can we interact with these "hairs" if they are all around us? Can we at least detect it? It seems that all question I and any non-specialist can ask are stupid and irrelevant, but it's still so exciting to think of all the possibilities.
It says in the article that the "root" is twice as far as the moon, and the "tip" is twice as far away as that. So the dark matter passes through the Earth momentarily (which I thought was accepted and the whole point of those deep underground observation experiments), but the "hair" itself forms quite far away. Hence the mention of being able to pinpoint one or more and sending a probe to gather information.
Re: Earth Might Have Hairy Dark Matter
#36I find this fascinating, but still purely hypothetical, yes? Basically: IF the observed expansion of the universe is indeed due to dark matter as we think of it, and IF such dark matter exist as streams, and IF such streams mix with ordinary galaxies, and IF the solar system is passing through such a stream THEN Earth MAY have dark matter filaments in its vicinity. IF we locate such a filament and send a probe, we mi…
The universe does not expand: www.cosmology.info/newsletter/2014.05.pdf I follow the BSM-SG model in which dark matter/dark energy is absolutely clear what it is and how it functions. The illustration is even a bit similar to the BSM-SG model, if you see it as the CL dimensions. Larger astronomical bodies have their own CL space, which means they carry a bubble with them those geometry is dependent on the body itself…
What I meant to say was: our observations with regards to expansion (or lack thereof). Thanks for the clarification (although you could have explained some of tho acronyms you used for the benefit of non-physicists).
Re: Earth Might Have Hairy Dark Matter
#37The edge of human understanding of the universe is a vague and scary place. When we dug deep below the atom level everything we took for granted fell apart. We had to invent an entirely new model of physics to make sense of our observations, which is complex and counter-intuitive (quantum mechanics) Would it be reasonable to assume that the same applies at the opposite end of the spectrum: from the sub-atomic to the…
The point I always make when this comes up is: epicycles, negative-mass phlogiston, æther and all the rest were good physics at the time. People who used them made more accurate predictions than any alternatives.
So yes, dark matter and dark energy are probably not the full story. But they are the best model we currently have, and it's very easy to criticize and much harder to offer a positive counterproposal.
Re: Earth Might Have Hairy Dark Matter
#38The edge of human understanding of the universe is a vague and scary place. When we dug deep below the atom level everything we took for granted fell apart. We had to invent an entirely new model of physics to make sense of our observations, which is complex and counter-intuitive (quantum mechanics) Would it be reasonable to assume that the same applies at the opposite end of the spectrum: from the sub-atomic to the…
Perhaps we don't have the capacity to understand how the universe works?
I can't remember where I read it but someone made the point that no matter how hard you try you can never teach a mouse to understand French.
Re: Earth Might Have Hairy Dark Matter
#39The edge of human understanding of the universe is a vague and scary place. When we dug deep below the atom level everything we took for granted fell apart. We had to invent an entirely new model of physics to make sense of our observations, which is complex and counter-intuitive (quantum mechanics) Would it be reasonable to assume that the same applies at the opposite end of the spectrum: from the sub-atomic to the…
That is exactly which brought me to the BSM-SG model. When nothing seems to fit well and the physics appear stranger and stranger, you should ask yourself: did we do everything right ? Did we do some mistakes in measurements ? Do we have some some wrong assumptions ? Turns out: yes. If you remove those wrong assumptions, you end up with a classic logical model that makes sense in very aspect. QM is just to raw for ex…
What are you talking about? QM is the most elegant, beautiful, and empirically verified theory ever. What does your "classical logical model" say about the Bell inequalities?
Re: Earth Might Have Hairy Dark Matter
#40This seems like something straight out of SciFi. Dark matter actually forming invisible rods that go through the Earth? Can we interact with these "hairs" if they are all around us? Can we at least detect it? It seems that all question I and any non-specialist can ask are stupid and irrelevant, but it's still so exciting to think of all the possibilities.
It says in the article that the "root" is twice as far as the moon, and the "tip" is twice as far away as that. So the dark matter passes through the Earth momentarily (which I thought was accepted and the whole point of those deep underground observation experiments), but the "hair" itself forms quite far away. Hence the mention of being able to pinpoint one or more and sending a probe to gather information.
> which I thought was accepted and the whole point of those deep underground observation experiments
Those are mostly neutrino detectors https://en.wikipedia.org/wiki/Neutrino_detector