/sci/ - Science & Math

I mean, maybe we just mis-measured the mass of the universe or whatnot?

Is that, like, within the realm of possibility?

And are we as alone in the universe as I am in this thread?

https://www.youtube.com/watch?v=7UNLgPIiWAg

It's possible. We might not understand gravity correctly, and it might behave differently at different scales.

But it's very unlikely.

>>8629456
What is dark matter is this
> all matter in the universe that is always in the shadow of planets closer to a sun

>>8629531
Sorry, meant to say it's very unlikely we don't understand gravity correctly. It DOES behave differently at smaller scales, but it might or might not at larger ones.

>>8629456
>Is there any chance that dark matter isn't real
Is there any alternative explanation of the
anomalous rotation of galaxies?

>>8629456
Yes, there is a chance.

>>8629571
Something like this?

>>8629456
Idk it in detail, but the lensing around certain galaxies requires more matter than can be seen. That and the amount of baryonic, dark matter, and dark energy adds up perfectly to a flat universe, a universe that can have a net energy of 0 and can arise from quantum fluctuations.

>>8629647
Could dark matter also just be matter that is in the shadow of the sun and planets? So that from our position we would never see the matter?

>>8629456
Yeah, there are definitely alternatives (MOND was the main one for a while, but in the past decade has suffered), but currently, it's by far the best. Of course you could always change up physics whenever you need to and find a way to make it consistent. The thing about dark matter is that it is a simple explanation that is highly predictive. It began as an explanation for the high rotation velocity near the exterior of galaxies (that required "missing mass). But once you take dark matter and run with it, you get something that matches predictions from the beginning of the universe (less than 1s after the Big Bang) to present day. Hell, you don't even get galaxies in simulations of the universe without dark matter! It helps us describe the cosmic microwave background, galaxy collision constraints, galaxy rotation curves, large scale structure formation, and even heat introduced to the universe during the recombination/reionization of hydrogen. Of course, there's always alternatives (and I actively look for them in my research), but dark matter is pretty perfect as far as we can tell right now.

>>8629786
It's not just that we can't see it (that makes it non-luminous); it's that it fundamentally doesn't interact with light or electrons except gravitationally (we know this from bullet cluster bounds and the CMB power spectrum of the early universe). This rules out any type of baryonic matter.