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/sci/ - Science & Math

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5355321 No.5355321 [Reply] [Original]

So why does dark matter "exist" again?

>> No.5355331

See your image. The factors are there, the result is there. Factor is missing.

>> No.5355332

too much gravity, not enough visible shit

>> No.5355333

Because data has implications.

Yew shur god me Yonny. I ave tott a listen.

>> No.5355337

We have calculated the mass of galaxies based on how they gravitationally interact with each other. We then look at the galaxies and add up all the mass we can account for using statistics like average mass of stars of various types, average number of planets these stars have, average amount of interstellar gas and dust, and find that the amount of mass the galaxy seems to have gravitationally cannot be accounted for by stuff we know exists. The discrepancy is rather large, so instead of blaming our counting, we posit that there must be something we don't know about that interacts gravitationally but does not interact in many other ways (so we cannot see signs of its existence by looking at light coming out of the galaxy, for instance). We call this stuff dark matter.

>> No.5355472

>>5355321
You have failed to realize the importance of profiling a missing piece of the puzzle. Do you lack the knowledge that this is how electromagnetism was discovered? You ignorant fool you have no place in science with your linear thinking. We draw the dimensions for missing pieces and experiment and grind until the bullet is bit to find the keys that lock these difficult questions. How the fuck do you think that the Higgs-Boson was found? IDIOT

>> No.5355504

Because the equations describing fermions are naturally invariant under supersymmetric transformations. The superpartners do not interact with electromagnetism.

Similar to how the generators of the electroweak group, SU(2) x U(1), naturally contain spontaneous symmetry breaking, and thus a Higgs field.

>> No.5355505

>>5355472
Lol, so much unnecessary rage. How did you even manage to get so upset by his relatively innocuous post?

Why does it always seem like my captchas have the word sanguine in them.

>> No.5355523

We don't know why it exists any more than we know why regular matter exists.

If you're asking how we know it exists, it's because we observe it, i.e. can map the sources of gravity that don't interact electromagnetically.

>> No.5355551

>>5355504
>generators of group
Any particular ones? I know a lot about these groups, but only from a pure math perspective.

>> No.5355556

>>5355337
Does such mass calculation make any assumptions about the nature of gravity? It seems like this a very large scale over very long distances...

>> No.5355614

>>5355556
We assume it falls off as the inverse square, and that this doesn't change with distance. We have no evidence to the contrary, so why not make that assumption.

>> No.5355677

So do the equations finally add up when you just add a bunch of dark matter?

>> No.5355744

>>5355677

We define dark matter as the all of the excess stuff, so yes, the equations do add up when you add dark matter in, but of course they do because we define it to be so.

Does that make sense?

>> No.5355775

>>5355614
Because your assumptions generate nonsense. That's why you invented dark matter - to resolve the contradiction, right?

>> No.5355817

>>5355775
This.

>> No.5355825

>>5355775
As opposed to assuming dark matter is non-existent thus GR is wrong despite no evidence to the contrary.

>> No.5355837
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5355837

>>5355825
>tfw /x/-men evidence is logical reasoning

>> No.5355910

>>5355825
I'm not saying it's wrong. I'm saying you've clearly got an edge case where your prediction is failing - just like pre-GR days when the Newtonians were working on their "ether" theories to make their equations work, but the extremely fast / extremely small cases revealed a deeper truth.

>> No.5355917

Except numbers are abstract concepts.

Gravity distribution is concrete.

Are you fucking mental

>> No.5355941
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5355941

>>5355917
>Gravity distribution is concrete.
lolqut

>> No.5355956

>>5355941
Wow, that was clever!

>> No.5355991

>>5355941
>Concrete distribution is gravity

>> No.5355992

>>5355956
Yeah well sure fine
But if you want to sass numbers for being abstract then you shouldn't be using a metaphor

>> No.5356003

>>5355321
google bullet cluster

>> No.5356007

>>5355992
1. That's the stupidest fucking thing I've ever heard.
2. It isn't a metaphor, it's literally another use of the word:
Adjective
Existing in a material or physical form; real or solid; not abstract.

>> No.5356015

>>5355910
Yes, this is another way of trying to explain the discrepancy. The problem with this is it doesn't fit the evidence as well as dark matter. We sometimes see things being attracted to areas where there is nothing at all. This wouldn't make much sense using a modified form of gravity (unless it was very complex, which is unlikely for a force so fundamental), so dark matter is the simpler explanation.

http://blogs.discovermagazine.com/cosmicvariance/2012/05/09/dark-matter-vs-modified-gravity-a-trialo
gue/#.UM0beY6AFE8

>> No.5356085

>>5356007
1. I'm sure it's not, I see that anonymity brings out your hyperbole. You should probably work on that.
2. "Gravity distribution" doesn't exist in a material form. It's a model, a pattern - just like numbers. If you disagree, care to say why rather than just restating your case in a crankier voice?

>> No.5356105

>>5356085
Gravitational effects are felt, they exist in the universe.

the number 2 does not.

I'm out

>> No.5356123

>>5356105
Shift the goalposts then take your ball home with you! That'll show 'em!

>> No.5356126

>>5356015
Thanks for the link; I'm reading about TeVeS now

>> No.5356182

>>5356105
Sensing and reacting to gravity ha evolutionary implications, sensing the number 2? Not so much. Learning it, yes, but sensing? No.

>> No.5356197

http://arxiv.org/abs/astro-ph/0608407

Apparently data collected during this collision disproved all current modified gravity theories, making dark matter the most probable explanation.