Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Cosmology Has Some Big Problems

blogs.scientificamerican.com

Post reply on HN
Print view View original

71–76 of 76 posts

Re: Cosmology Has Some Big Problems

#71

Post by hannasanarion »

slowmovintarget wrote: post #65
whatshisface wrote: post #37

Earlier quoted context omitted.

To be clear, they're not inconsistent with the theory of dark matter, they're inconsistent with those galaxies specifically having dark matter. The author was wording that in a confusing way.

To be even more clear, "dark matter" isn't a theory. It is a name for something we need theories about. I wish the article had made that apparent.

Dark matter is a hypothesis, and one that makes pretty strong predictions, several of which have come true, so it's not inappropriate to call it theory.

The phenomenon of galaxies demonstrating significanty more mass than their sum of normal matter is the observation that is explained by dark matter.

Re: Cosmology Has Some Big Problems

#72

Post by AnimalMuppet »

jerf wrote: post #64
AnimalMuppet wrote: post #33

Earlier quoted context omitted.

Yes and no. Yes, we're seeing gravity waves and radio waves and gamma rays and near infrared and millimeter wave and neutrinos, and maybe a few others that I forget. We're way past human senses, or any animals. And yet I keep thinking of a deaf species that runs across Beethoven's Ninth Symphony. They can put an oscilloscope on the pressure waves in the air, so they can "see" what's going on. They can study the diffe…

I actually think there's a bit of an answer to that, in the No Free Lunch theorem. To "experience" Beethoven's 9th Symphony, you need cognitive biases that it can tickle in the way that Beethoven intended. An alien missing those biases won't "get it", but then they'll get things we won't. But there's no solution to having the right biases for everything. All we can do is throw a lot of things at it and hope for the b…

I wasn't suggesting that we should be other than ourselves - just that, by being ourselves, there are things that we don't "get", even when we can see the data.

Re: Cosmology Has Some Big Problems

#74

Post by eaim »

All said and done, the current state of cosmology (whether one falls in with mainstream theories or not) is a mess. It has so many addendums, codicils & caveats that one has to be almost a type of lawyer of physics to be able to navigate it. We await our new Einstein. Our new Heisenberg. Our elegant theory of everything; or as one science writer put it: The universe on a T-shirt.

Re: Cosmology Has Some Big Problems

#75

Post by eaim »

astro123 wrote: post #31
scrozart wrote: post #24

Earlier quoted context omitted.

> > Today's space telescopes provide no direct view of anything > I have no idea what that means. They literally observe the sky... Seriously! At this point they're just spitballing.

I was maybe a bit too cavalier here. I think I understand what the author means - the data that they gather is understood in the context of the model that we think is best. But, it isn't as if cosmologists are rigidly holding to the model. Here's a paper looking at extensions to lambda CDM https://arxiv.org/abs/1512.05356 . As I mentioned, changing GR is being looked at as an alternative to DE http://www.resceu.s.u-t…

Sorry but I’d have to disagree: There are plenty of people working on cosmologies that don’t include the Big Bang, or that do include it but only as one facet of a larger theoretical framework.

As for not being able to imagine how you explain the CMB without the Big Bang, well, there are plenty of good arguments being made here that put to paid that “limitation.” As well, think of the Michelson-Morley experiment. In that era, no one could imagine how light could propagate through space without the presence of a medium permeating that space.

I’ll venture one step further. Dark Matter is to current cosmology what the aether was to 19th century cosmology.

Post reply on HN