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/sci/ - Science & Math

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4607509 No.4607509 [Reply] [Original]

Why do people believe in dark matter? It seems kind of ridiculous to me that so many people believe something and have no evidence to back it up

>> No.4607510

And don't even get me started on dark energy

>> No.4607522

>no evidence to back it up
http://en.wikipedia.org/wiki/Dark_matter#Observational_evidence
Lolz.

Seriously, either GR is totally wrong, or there's some sort of dark matter sitting around. People have tried playing around with GR, but they found it ridiculously hard to modify GR in a self-consistent manner that matches everything we see today...

>> No.4607524

It's not a belief like fairies or dragons. It's a place holder for something not understood. Without the place holder, the 4% doesn't make sense.

>> No.4607528

There's not evidence against it, therefore it exists! QED.

>> No.4607533

>>4607522
That isn't evidence, that is people not understanding what they see and making shit up so the rest of what they say makes sense.

It is absolutely ridiculous

>> No.4607538

physicists like to make up shit and believe it

>> No.4607542

>>4607538
>>4607533

>daytime in the US
>troll posts greatly increase

>> No.4607545

>>4607542
Are you implying there is any reason to believe in dark matter?

>> No.4607549

>>4607522
But observations of matter are purely relative to the observer said Einstein. So how do we know that it isn't something we already know exists just moving in a unique way.

>> No.4607551

Fucking twelve year old or troll post. Do you even know the basic laws of orbital mechanics?

Sage sage sage

>> No.4607552
File: 21 KB, 300x225, Don__t_feed_the_Troll.jpg [View same] [iqdb] [saucenao] [google]
4607552

>>4607509
>>4607510
>>4607528
>>4607533
>>4607538
>>4607545
>>4607549
Yay for idiotic trolls. Don't feed them, gaiz!

>> No.4607555

>>4607552
not one of them but I'm genuinly curious about the topic, and if one cannot get serious answers, how do you want them to stop asking?

>> No.4607556

>anybody who questions our theories (even if they have no evidence to back them up) is a troll or a heathen!

Why does science seem more like a religion these days than actual science.

>> No.4607564

Itc's just because YOU OP are a vitim of hype and media, without learning what's really going on.

I'm going to try and forget that you even accused scientists of "believing" it. Because it will probably lead me to think that you are either a troll or just very uninformed as to how science works at all.


So to remain productive I will answer your questions.
People don't believe in dark matter. As an example of this, you can ask any physicist if dark matter must actually be matter, they should tell you "no".

Here is what we know.
1) The only thing that gravity acts on is matter/energy.
2) We OBSERVE that the pull of gravity in galaxies is much higher than is accounted for by the matter that we see in those galaxies.

CONCLUSION: There is SOMETHING, let's call it X, that is causing this extra gravity.

agree?

So what do we call it? "X" isn't a very meaningful term... it tells us nothing about what phenomena we are describing..
Well, since we have an abundance of gravity let's call it "dark matter" since we know gravity acts on matter yet we can't detect it so we add "dark" to the front.

Does it mean that we are saying it is matter for sure?
NO

Does it mean that we "believe" (lol) that it is matter?
NO

Does it mean that we think matter is (at this moment) the most likely candidate for explaining this OBSERVED phenomena?
YES

Will anyone but the media and people like you be surprised if dark matter turns out to not be any form of matter/energy at all but something we haven't even considered at this stage?
NO


(Sorry if I sound upset, it pisses me off to no end when people accuse scientists of "believing" something.. It just undermines everything we do. Please NEVER use that word when talking about science ever again)

>> No.4607566

>>4607564
>The only thing that gravity acts on is matter/energy.
We only "know" that because we made up dark matter to "prove" it

>> No.4607568

>>4607509
Why do people use pie charts that serve no visual purpose?

>> No.4607575

>>4607568
It was the only picture having to do with dark matter that I had on my PC

>> No.4607581

Maybe because it's a theory?...

>> No.4607582

>>4607566
the hell are you talking about? Seriously that was just retarded..
That was our stance long before dark matter was even thought of.

Furthermore, nothing is ever final in physics you moron. There is no "proof" that matter/energy is the only thing gravity acts on. I only said "know" because I just didn't think anyone would take it literally.

You should read it as the only thing we "know of" which gravity acts upon is matter/energy.

>> No.4607583

>>4607566

3 + x = 5

Look guys, I just made up "x" to "prove" that my equation equals five.

Am I a scientist yet?

>> No.4607586

>>4607566
also thanks for covering up the best post in this entire thread with your stupid ass fucking response.

now nobody is going to see it.

Anyone genuinely interested in what OP is asking just read this:
>>4607564
>>4607564
>>4607564
it covers everything.

>> No.4607587

yeah, scientists are essentially like christfags when it comes to believing in dark matter

>> No.4607589

>>4607586
>covering up
Nobody is this retarded, are they?

>> No.4607594

>>4607589
>DURRR there's only 1 meaning of every word in the english language.

ya man I meant it's a fucking conspiracy.
You/or whoever that was pushed the post to the top so in no longer appears on the front page. "covering it up" I never said it was intentional,
but that waste of space post made the good post less visible.

>> No.4607599

>>4607594
So you're made because people are posting on an imageboard?

>> No.4607600

because it's there

>> No.4607605

So how come we don't just assume that matter from adjacent universes is acting on our galaxies? Why do we have to invent a mystical invisible matter that effects everything?

>> No.4607608

>>4607605

because "dark matter" doesn't entail anything other than the stuff which makes the gravitational field strong enough to hold galaxies together whatever the fuck it may be

>> No.4607610

>>4607566
>>4607583
No one's trying to prove anything. Did you actually read >>4607564 or what?

We don't know what it is. We'd like to know what it is, but at the moment we can only make educated guesses. Why are you so butthurt about this?

>> No.4607611

>>4607599
No, it's just fucking annoying when you type out a full length response that covers everything the OP is asking completely,

and then some dicks come along and take ONE word way out of context and say
>derp, "We only "know" that because we made up dark matter to "prove" it"

and then after 5 seconds your post is no longer visible on the front page meaning that everyone now entering this thread thinks it still hasn't been answered and maybe someone who actually doesn't know any better, instead of reading the answer:
>>4607564
is going to be led to think that scientists just go around "believing" this and that all day, and prescribing words to situations and taking the meaning literally.

>> No.4607613

>>4607611
Has anybody ever touched your penis before? You get angry at the most ridiculous things

>> No.4607615
File: 98 KB, 239x254, Rape-Mario to death.jpg [View same] [iqdb] [saucenao] [google]
4607615

>>4607605
>mystical

>> No.4607618

>>4607613
This is the quality of post I've come to expect from someone who has just been told.

Most people are incapable of admitting when they are wrong during arguments so they resort to this sort of thing.

But it's ok, I know what you really meant.
Apology accepted.

>> No.4607626

>>4607613
>aw man >>4607611 made a reasonable post and had some good points against my retarded spewing
>TIME TO WHIP OUT THE AD HOMS

>> No.4607629

>>4607618
I wasn't wrong though, nobody has evidence of dark matter.

I was just pointing out how you were getting mad at somebody for posting on an imageboard. I literally could've posted anything and you would've gotten mad.

>> No.4607635

>>4607509
Because we don't understand how vacuum or occupied space expand or contract.
>>4607564
What are the large scale effects of Relativity on matter?

>> No.4607636

>>4607629
read
>>4607564

>> No.4607640

>>4607636
Do you believe in gravity?

>> No.4607655

>>4607635
I don't know. But how is that relevant?

Are you just going to attack that one line again like everyone else is doing?
The point still stands even if you take it out. That point is to ignore the term "dark matter" if you want.
Call it whatever you the hell you want to call it. All we are saying is that there is something causing gravity to be stronger than it should be by current estimates.

Possibilities include:
*corrections to one or more of several different theories we currently have
*an extra, as of yet undetected, form of matter floating around galaxies
*other things that I can't think of

sound reasonable to you?
If so great.. you can stop there.

The rest of what I was saying is simply to describe WHY we chose to call it dark matter, but IT DOESN'T IMPLY THAT IT IS MATTER

>> No.4607654

ITT: people telling others to read their posts because they think they made the most insightful comment in the history of science

See: this post.

>> No.4607656

>>4607654
I'm pretty sure it's only one guy and I'm pretty sure he hasn't left his house in at least 3 months.

>> No.4607662

>>4607640
No.

I understand that the result of gravity is the most likely outcome considering that it has not once been observed to not occur in even a single atom.

It is possible that all particles just move randomly and the observed effect of gravity is only a coincidence of their movements and their is no real force between them at all.

That is a possibility, but the odds strongly suggest that there is a mechanism. We call it gravity.
We go with what is most likely. We can never prove to exactly 100% certainty but we can approach that limit.

>> No.4607665
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4607665

>>4607662
>he doesn't believe in gravity

>> No.4607669

>>4607654
>>ITT: people telling others to read their posts because [it's the only reasonable answer to OP's question in this entire thread and they don't feel like typing it out again and again when it's already there]

FTFY

>> No.4607671

>>4607655
Assuming dark matter, a as of yet undetected hypothetical material is the cause, why is it localized then? This is probably tied to the cosmological "constant" on some level.
If space time's collapse/compression is equivalent to a black hole or a dense galaxy, then space time's extension/expansion is equivalently tied to big bang/void.
>In B4Neutrinos.
There's something were obviously missing, what is dark matter in the quantum framework in this instance?

>> No.4607674

>>4607665
that's actually not funny at all..

Belief in anything is retarded. You can probably get away with believing in gravity if you want because the alternative is a STATISTICAL impossibility,
(although it still remains a possibility nonetheless).

I on the other hand won't say I believe something unless there is an exact 100% certainty.
In other words, I don't believe in anything at all.

If you want to bet on gravity, everyone will bet that it exists because the odds are astronomically in favor of it. But if you think there is a 100% certainty then you need to think again.

>> No.4607676

>>4607662
Temporal Phenomena, not a force.
Good luck detecting those Bosons.
>materialistic framework

>> No.4607709

>>4607676
never said it was a phenomenon at all.

Take all the possible configurations of a set of random particles.
and then take all possible sequences of the elements of that set.

There will always exist a sequence that someone looking upon it would see a pattern from one configuration to the next. In this case we might see that the particles all seem to be attracted to each other, when in fact what we are actually looking at is simply a sequence of random configurations.
No actual force between them.


Think of the universe as this little experiment. Consider for a moment that particles only moved randomly (no force, no gravity).
One possible sequence of configurations of the particles would appear as gravity did exist even though it didn't.

Since that is an explanation and 1 such outcome exists as the universe we observe, then that itself prevents us from saying gravity exists with 100% certainty.
The number deviates from 100% by such a tiny amount there probably is no possible way to even represent it.
It is unimaginably inconceivably tiny, but it still deviates from 100% nevertheless.

So no.. we do not know with absolute certainty.

>> No.4607714

>>4607510

Welcome to religion.

>> No.4607741

>>4607709
>No actual force between them.
Well black holes need to be explained then, was it just an electromagnetic force that caused their collapse?

As for gravity it's self relativity taught us about time dilation at higher energy densities and speeds in relation to light, on a "large quantum scale" [lol that bs] what effect would this have on large objects if not to induce a sinkhole of time?
Potentially explaining why we can't detect anything in regards to observed data and the requisite particles/bosons.
Right?

>> No.4607770

>>4607509

>In 2150, scientists discover that there is in fact, no dark energy at all but that space has a special property which is resisting inflation, making up for observation
>futurelaughingwhores.jpeg

>> No.4607780

this is fucking retarded

>> No.4607786

>>4607780
Whys that?

>> No.4608040

>>4607741
How would you prove that matter contracts space-time and void expands it?

>> No.4608053
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4608053

>troll thread
>50 replies

>> No.4608061

>>4608053
I'm honestly curious what everyone has to say about this. Especially considering no one has detected dark anything. No one really has any answers for any of this since they seem caught up in a materialistic, quantum, or relativistic framework. What is actually holding galaxies together?

>> No.4608079

Dark matter was invented so people can talk about ether without calling it so.

>> No.4608084

>>4608079
No, ether is something else entirely.

Spacetime was invented so people can talk about ether without calling it so.

>> No.4608088

>>4608084
>Spacetime was invented so people can talk about ether without calling it so.
Relativity... *Dat time dilation

>> No.4608097

What a shitty troll.

>> No.4608103

That realization that /sci/ has no memory for theories. I wanted to hear some explanations but you guys are just gonna call everyone with a legitimate question a troll, I'm not OP, but I was curious.
>no imagination

>> No.4608116

>>4608103
>Not even trying to understand what dark matter is
>Expecting people not to call you a troll

>> No.4608128

>try to explain
>YOURE JUST WORKING WITHIN A FRAMEWORK

And you're working within a solipsistic "explain it to me without using science" framework.

>> No.4608131

>>4608116
You don't even know what it is, give me some details, what is this mysterious undetected thing, clearly you must have some expectation of it's properties. Right?
I was just throwing it out there that it could be a different phenomena entirely, while many try to detect them, other explanations may exist.

>> No.4608149

>>4608131
>Much of the evidence for dark matter comes from the study of the motions of galaxies.
They got nothing, reading >>4607522 's link
>>4607741's
postulation could be equally valid.

>> No.4608156

Dark Energy isn't an actual entity. We know invisible matter, ala Dark Matter, exists. It physically has to and I remember something about us observing it indirectly a few years back.

However, that 74% of Dark Energy is not something real. The mathematics states that there has to be 74% of SOMETHING influencing gravity in the Universe for everything to be the way it is. We dont know what the fuck it is, so we just call it Dark Energy.

>> No.4608157

>>4608149
>arguing using Wikipedia

>> No.4608163
File: 241 KB, 1360x1360, bullet-cluster-square.jpg [View same] [iqdb] [saucenao] [google]
4608163

>>4608149
pic related.

This image is the best evidence to date of dark matter.

It is an image of two clusters of galaxies colliding, so it is absolutely massive.

According to the gravitational lensing they are able to determine the distribution of mass, the blue represents just that.
Whereas the red color represents the actual normal matter distribution of the galaxy clusters.

Usually the two are on top of each other (only that the gravity should be stronger if there is dark matter, but they should still be together),

but this is strongly in support of our predictions, if dark matter really is a form of matter that is just very weakly interacting, then we would expect that the dark matter is able to pass through the collision much more easily than the normal matter is.
So the normal matter is slowed down after the collision and there is more of it towards the center, but the weakly interacting dark matter is able to mostly continue on its original trajectory unaffected.

>> No.4608215

>>4608157
Implying everything there is completely fake 100% of the time, what other evidence is there? Recalling my astrophysics that was the only real "solid" evidence for it
>>4608156
WIMPs are a useful keyword after looking into this a bit more... I guess there is some kind of indication matter/energy is behind it.
InB4 Higgs boson.

>> No.4608214
File: 19 KB, 400x300, introduction to gravitational lensing.png [View same] [iqdb] [saucenao] [google]
4608214

The observational evidence for dark matter is something called "gravitational lensing".

Imagine you're looking at a distant galaxy (not in our cluster). Directly in your line of sight is a massive galaxy cluster (which is also quite far). The light emitted from the galaxy behind the cluster is emitted in all directions. Imagine the rays that are emitted at such an angle as to be tangent to an edge of the cluster. In other words, imagine the rays that are not going towards the cluster, but just slightly to the side of the cluster. By general relativity, the massive galaxy cluster warps spacetime, and the photon, going straight, is actually seen, by us, as curving. Now this ray of light is bent, and although it would otherwise never reach us, it is bent in a way that it reaches us directly. Project backwards from the angle we receive the light at, and that's the galaxy's apparent position in the sky.

Now through standard candles like type Ia supernovae, we can determine exactly how far the galaxy is. Combining that with the angle, we can project where the galaxy is. But this projection is if the ray of light followed a straight path. In reality, it was bent.

Now imagine another ray, going in a different direction, also trying to just go past the massive cluster. Its also caught by the warped spacetime. Its trajectory is bent. It happens to also be bent towards us. Now we project this ray back, and use standard candles to determine the distance. To our surprise, it's the same galaxy, only now it appears to be somewhere else. So you get this sort of lensing effect, resulting in a warped view of the galaxy, stretching and bent around in a ring around a massive galaxy cluster.

>> No.4608220
File: 109 KB, 1014x670, gravitational lensing.jpg [View same] [iqdb] [saucenao] [google]
4608220

>>4608214
So what is the point of all this?

Well the amount of gravitational lensing you observe relates to the mass of the object causing this phenomenon: the galaxy cluster. But our estimates of the mass in the cluster cannot nearly account for all the lensing that is actually happening. No matter what wavelength we observe in, we can't see any more matter.

But something is causing more mass. Something is warping spacetime more than the galaxy cluster could be doing all on its own. This is dark matter. We have no way of directly observing it, and yet we observe its effects. We observe the gravitational effects of this mass, as we would any mass. And so we infer that it is there.

>> No.4608253

>>4608220
If dark energy is associated with concentrations of matter like galaxies, like we know dark matter is, and we don't detect it down the road could that imply another force at work?

>> No.4608262

>>4607509

>2 billions christians in the world

>> No.4608292

Rotation curves is another way we justify dark matter.

If you measure the rotational velocity of an object in any galaxy with respect to its distance from the center, you'd expect it to obey Kepler's laws. After all, most of the mass of, say, a spiral galaxy, is in the center where the supermassive black hole is, right?

Kepler's laws of planetary motion and Newton's laws of gravity imply that the further away a body is from the center of mass it orbits around, the slower it orbits.

We always see the same pattern when observing a spiral galaxy: the rotation curve (orbital velocity on y-axis, distance from center on x) is upside-down. The further something gets from the supermassive black hole, the FASTER it orbits.

There are two ways to reconcile this: either throw out Newtonian gravity and Keplerian planetary motion, or a massive dark matter sphere that contains the galaxy (which means most of the mass of the galaxy is everywhere, not at the center of the visible part). If the latter were true, the rotation curve is exactly what you'd predict.

Classically, you'd make your theories fit the data, not the other way around. So you'd have to revise the laws or throw them out. It's not something we do lightly to say that there is an undetectable dark matter which is so pervasive in the universe. Its only once you combine rotation curves, the Bullet Cluster, gravitational lensing, large-scale structure, and a lot more, that you finally accept that perhaps there really is dark matter.

>> No.4608299

>>4608253
Another force at work doing what? Causing the lensing?

Dark energy has even less evidence than dark matter, its mathematically implied because the expansion of the universe is accelerating.

>> No.4608315

>>4608299
Is the expansion uniform?
Or are we currently unaware?

>> No.4608332

>>4608299
Again.. Your problem with "dark energy" is literally nothing more than your inability to see past the name.

You are exactly right, that is the only evidence we have. So what conclusions can you draw from that? Does that prove that it has to be energy?
I'm sure you answered no... and I'm sure you aren't that arrogant to think that you are able to see it and every other scientist in the world is too stupid.

Trust me... we all fucking know... It's just a name...

"dark energy" is just a name... "dark matter" is just a name.
Get the fuck over it already.

Scientists did NOT just say
>>"we mathematically need energy here to account for this therefore energy! and it's dark!"

instead they said:
>>"something is wrong.. it could be anything.. a problem with our equations even... what should we call it? idk... oh hey you know what? IF we had some other form of energy it could possibly explain it... well at least that's one idea... perhaps we could just call it "dark energy" even though we really don't know what it is.


The point is that people think that "dark energy" is a proposed answer to why the universe is expanding at an accelerating rate.
But that's actually a bit of a misnomer, "dark energy" refers to WHATEVER the hell it is that's causing it. Even if it's a problem with our current understanding and has nothing to do with energy at all.


Same exact thing can be said about "dark matter".
It's just terms that are given to the unknown solution instead of the problem.

>> No.4608348

>>4608332
So basically what I'm saying is that asking:

>>what is the evidence of dark matter and dark energy?

is completely meaningless. Instead I think what the people in this thread are actually trying to ask is:

>>what is the evidence that dark matter is actually some form of matter, and that dark energy is actually some form of energy?

THAT'S what people are really asking.

Asking the former question is like asking:
>>what is the evidence of "x" in the equation x^2=4 ?
just like above, this is meaningless, the only reasonable question would be something like:
>>what is the evidence that "x" is 2 or -2 in the equation x^2=4 ?

>> No.4609225

>>4607509
(Introduction to modern cosmology) 'A Universe From Nothing' by Lawrence Krauss, AAI 2009
http://www.youtube.com/watch?v=7ImvlS8PLIo