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comment by kantos

Dark matter sounds like the modern day equivalent of believing there's only earth, fire, water, and air elements. We know there's more to it and once discovered, our understanding of the laws of the universe could be radically changed for the better. Just hope it happens in my life time. In the meantime, guess it's back to the drawing board.




francopoli  ·  200 days ago  ·  link  ·  

I like to describe it this way. Don't think of it as "dark matter." Think of it as "dark gravity." SOMETHING is out there acting like a gravitational force. SOMETHING out there is bending space in very predictable ways that we can measure, test, and make predictions about. We know what this "force" is NOT. It is not the normal matter that makes up the stuff you and I and the stars are made of. It is not clouds of gas and dust. IT is also very cold and does not interact with normal matter and light or if it does interact it does so very weakly.

And the kicker is that when you make an energy budget for the whole universe, this "dark gravity" makes up 4x more of the universe than the stuff that you and I are made of. And stuff that is unknown makes me excited to be alive. Maybe this will be the solution to every issue we face as a people. Maybe it will be something we cannot use and exploit. Maybe it will be unknown for dozens of generations until we get a mind and the tools needed to say "Oh, that is what this force is."

The fact that humanity found something out in the universe that is driving the researchers bonkers makes me excited for the future.

historyarch  ·  196 days ago  ·  link  ·  

I like reading about this sort of thing but have no background in physics so I appreciate your explanation. Dark matter and dark energy are different, but related as I understand it. Does dark matter create dark energy or am I thinking about this incorrectly?

One wonders if the answers to dark matter questions will shed light on the "space" between Newtonian physics and quantum mechanics. Perhaps the answer as to what dark matter/dark energy will lead to a unified theory and help explain other mysteries such as how photons seem to act as a wave, particle, or both (the double slit experiment) or how electrons can appear to be in 2 places at once.

kantos  ·  200 days ago  ·  link  ·  

    And the kicker is that when you make an energy budget for the whole universe, this "dark gravity" makes up 4x more of the universe than the stuff that you and I are made of. And stuff that is unknown makes me excited to be alive. Maybe this will be the solution to every issue we face as a people. Maybe it will be something we cannot use and exploit. Maybe it will be unknown for dozens of generations until we get a mind and the tools needed to say "Oh, that is what this force is."

Don't have much to add, but I'm smiling like a goon with agreement.

historyarch  ·  196 days ago  ·  link  ·  

It reminds me of the old theory that space was made up of a medium called ether.

tacocat  ·  200 days ago  ·  link  ·  

It's more like a mathematical outlier that scientists use to reconcile what really seems to make sense with what we see. I think most physicists were skeptical of it.

It's really just matter that doesn't emit light. Makes sense on paper. My eyes start to cross when they get into dark energy.

I've always been skeptical of it. But I'm an artist, not a scientist. You can tell me something makes the math work. That doesn't mean I understand what the fuck that means

Devac  ·  200 days ago  ·  link  ·  

    It's really just matter that doesn't emit light.

Oh, it's much funkier than that. It's not just lack of emission, it's the lack of any interaction between light and dark matter. There's no refractive index, no ability to reflect or absorb light, no known way for it to cast a shadow and (to my understanding) there's no effect similar to radiation pressure. You might as well forget about anything relating to (classical) optics when you are talking about dark matter.

I don't know about most physicists being sceptical, but IMO it's a very interesting concept, even if it would turn out that it's about as good as luminiferous aether.

tacocat  ·  200 days ago  ·  link  ·  

This matter doesn't behave normally?

Maybe not skeptical but more like this is very suspicious. Yeah. That sounds like skepticism. I don't speak for the scientific community. Disregard me. I sucks cocks.

Devac  ·  200 days ago  ·  link  ·  

    This matter doesn't behave normally?

If by 'normally' you mean 'like any other matter we interact with and detect directly on a daily basis', then no. Dark matter interacts gravitationally and we can observe this effect via indirect means. Weak gravitational lensing around galactic clusters is attributed to it. There are also attempts to work out how a collision of dark matter particles would work since it's not unreasonable to assume we could observe some of the resulting products.

Unfortunately, between it being unobservable directly through optical means and dozens of possible explanations of what dark matter is (or how to work around it), it's a very hard problem to reconcile. It's understandable to be suspicious of it, but time will tell. Hopefully it's gonna happen while we are still alive.

    Disregard me. I sucks cocks.

No. And there's no need to brag.

tacocat  ·  199 days ago  ·  link  ·  

But I didn't even say how good I can suck a cock...

kantos  ·  200 days ago  ·  link  ·  

The answer to the first question is yes and no from my fuzzy memory, but Devac and francopoli are both clearer and better informed. And together they give a kick-ass answer. As to skepticisms across communities...

Astronomy professors rave about how nutty it is that the only way we can measure it is through our understanding Newtonian mechanics alongside the implications.

Physics professors acknowledge it's existance for the same reason, then smile and shrug off preceding questions.

The lone math professor who deals with astronomy I talk to flat out calls the above lunatics.

I'd love to say that's how each community thinks, but I've got a small sample size.

EDIT: Left off the beginning of the last sentence.

francopoli  ·  200 days ago  ·  link  ·  

    Astronomy professors rave about how nutty it is that the only way we can measure it is through our understanding Newtonian mechanics alongside the implications.

Special Relativity, not Newton, but otherwise spot on. History is full of these "I have no idea on the why or how, but here is a bunch of math to describe and make predictions" when it comes to natural phenomena. Hell, speaking of Gravity, what is it? I mean Why is there Gravity? We understand DNA and evolution magnitudes more in depth than we do one of the four universal forces of the universe!

Devac  ·  199 days ago  ·  link  ·  

    Gravity

This is obviously just one of the more mainstream theories, but I found a very nice lecture series that tries to explain/ground concepts of loop quantum gravity. No maths but also no stock animations of vibrating strings. ;)

kantos

kantos  ·  198 days ago  ·  link  ·  

Hitting this up after Passover tonight. Fucking love TierZoo, in case I haven't said that enough.

Dala  ·  199 days ago  ·  link  ·  

I think you have just introduced me to my new favorite website. Thanks!

Devac  ·  199 days ago  ·  link  ·  

My pleasure! I'd also urge you to check out either of Brian Greene's Special Relativity courses they are hosting (there's one purely conceptual and one formal), even you if are already familiar with the material. It's hands down among the best lecture series in physics I watched and I strived to emulate some of his style in my own outreach work.

Dala  ·  198 days ago  ·  link  ·  

Everything they have looks like something I will enjoy, but I will make sure to put those high up in the queue!

kantos  ·  198 days ago  ·  link  ·  

Ahh, expecting to learn more about this next semester, but the survey course spoke related it all back to conservation of angular momentum to explain the confusion around why the galaxies' rotations don't add up.

tacocat  ·  199 days ago  ·  link  ·  

Gravity is a myth and we live on a flat disc accelerating upward. Check and mate

user-inactivated  ·  200 days ago  ·  link  ·  

One time one of my coworkers was just staring off into space. I asked them if they were okay and they just kept on staring, and said "I know it's a meme and all, but seriously, how do magnets work?"

francopoli  ·  200 days ago  ·  link  ·