Thread: Dark Matter and Dark energy

Having searched the internet vigourously, i have yet to find a satisfying description of how we can know about the existence of either Dark Matter or Dark energy.
It is frequently reasured that we neither know what dark mater and dark energy are, and have yet to prove there existence. As far as i can find out, the only thing telling me, and other inquisitive people, about how we know there is Dark matter and Dark Energy is a graph on wikipedia: and nemorous comments saying that dark energy is the cause of the unerverse expanding.
Whilst i recognise that there is no proof for dark energy, I beleive that there must be some foundation onto which the idea of Dark Matter and Dark Energy is based, as it can not possibly be that someone said "hey, i know what, I'll say theres this weird stuff that can't be seen or obsevered and i will call it dark energy, and i will say that it makes up 70% of the universe" - this just doesnt seem plausible...

I hope that i made myself clear, I understand that the universe is expanding, and the evidence for it, and that proof of dark matter can not be found, however i do not understand where the idea of dark matter came from.

Dark matter was hypothesized after looking at the rotation curves of galaxies. Google 'rotation curves' and you'll find more info. I think Wiki has a good write up about it.

Dark energy was hypothesized after observations of distant type 1a supernovae with high redshift. See work done by Saul Perlmutter et al. and Filippenko, Kirshner, Garnavich et al.

Happy hunting,
william

Ironic that this is just after it was on the science channel. I'll say this: Dark matter, dark energy, etc, is utter bullshit. at best, the only way they could explain it's existence is the simple blackness of space. Nothing has to be something, right?

Here's something simple: They say that everything in a galaxy moves at the same pace. When in fact the farther out it goes the weaker the centers pull should be. Basically, common law of gravity. It's applied to the solar system with perfect precision and to the galaxies.

MINUS ONE FATAL FLAW: they only count the center. They don't calculate the precise gravitational pull every star has on another star. In our solar system, the heaviest object next to the sun at best balances out the solar system a little. the suns gravity mostly cancels out the majority effect it has on the other planets. Plus, none of them are big enough to really dominate anything after a certain distance.

Now it's an OBVIOUS logical fallacy to say that the galaxy acts exactly like our solar system. That's an apple-planet comparison. Since the planet is 9000x (and more) bigger than a small little apple, the same assumptions can't apply.
Basically, here's an off-the-top solution: All the stars in the galaxy, star clusters, supergiants, black holes, etc, rotate around a "center' which is suggested to be a massive black hole. Outside the black hole there are billions of stars packed closely together in one really brilliant display of lights and fireworks. All these stars tug on eachother and spin rather rapidly around the supermassive black hole.

Outside that, the stars gravitational pulls tug on other stars, and speeds them up to their speed, and outside that the quicker stars tug on more stars and bring them up to relatively the same speed.
Meanwhile, the stars nearer to the center have such a high amount of gravity (a lot of mass afterall) they are ALSO effecting stars farther out. And so on and so forth.

Why doesn't this work in the solar system? It does! At different levels! certain planets slow down and speed up other planets very very slightly. Imagine a galaxy scale, now, and we've solved a galaxy rotation/gravity problem.

Yeah, dark matter is the answer. not. Sure it "solves" the problem, but...thing is, scientists basically added a bunch of hypothetical guess-matter to a model. Which conforms to current gravitational laws. It's just as likely as *MY* explanation up above, if not LESS! As a computer model produced by one resource group shows, DUH it would work. Does it mean it happens or exists? No.

And while I'm at it: Dark energy/matter also explains the energy in telekinetics. Hah, now lets see who supports it.

Skepticism! USE IT! And f34r my poor explanation.

----edit----
The almost same explanation works for the galaxies speeding up rather than slowing down. As galaxies tug and pull on eachother, they speed up faster and faster until the collide. This collision probably slows it down some, but a lot of speed remains. Billions of galaxies are pulling on eachother continually, and continually speeding themselves up (some getting closer, others being flung away as they pass by).

Seriously, I know little about the mathematics required here, but use some abstract thought you bloody scientists!

Take no notice of Jeremy, and his 'BS' comment, he's just the nearest thing the forum has to flat earther...

There is some maths (as William pointed out) that dark matter exists, that is any matter which does not radiate heat energy and is thus at absolute zero (or close) also it needs to be far away from any source which may 'bounce EM energy off it' If the moon was halfway between the sun and the next nearest star it would be 'dark matter'. So all those dead/failed stars, solar systems etc can be classed as a type of dark matter. Anyway that's my understanding, and to Jeremy I would say "be open minded like I am..... :wink:

Originally Posted by Jeremyhfht

Skepticism! USE IT! And f34r my poor explanation.

Seriously, I know little about the mathematics required here, but use some abstract thought you bloody scientists!

Good advice.

But do you really think no one has thought-of/accounted-for the objections you propose?

So when would you like your Nobel Prize?

Ever heard of Gauss' law as applied to gravity? Sorry... but you're about 150 years too late, and a bit mathematically inadequate....

So nice to know I just get flamed rather than given some reason as to why I'm incorrect. I'm done here.

Originally Posted by Jeremyhfht

So nice to know I just get flamed rather than given some reason as to why I'm incorrect. I'm done here.

No reasons??? :?

Originally Posted by william

Have you ever heard of GAUSS' LAW as applied gravity?

Your "abstract thought" has been known and taken into account for more than 150 years....



But... if you really want a piece-by-piece rebuttal, we're not supposed to do others' homework... but okay....

Originally Posted by jeremyhfht

MINUS ONE FATAL FLAW: they only count the center. They don't calculate the precise gravitational pull every star has on another star.

Who told you that??? There's a fatal flaw in your "fatal flaw."
How dumb do you think the scientists are? This was my reference to Gauss' law. Plus, the numerical modelling done using Eularian (e.g., adaptive mesh finite-difference & MHD methods) and Lagrangian (e.g., smoothed particle hydrodynamics) schemes automatically take into account all the particles of the galaxy.

And while I'm at it: Dark energy/matter also explains the energy in telekinetics. Hah, now lets see who supports it.

If you don't explain how this works, then I won't explain how dumb this is.

The almost same explanation works for the galaxies speeding up rather than slowing down.

If this is a reference to dark energy, then you have a fundamental misconception of what it is that dark energy is supposed to explain. Try Google or Wiki.

N.B. It's okay to propose ideas such as the one you have. It's even okay to be wrong (heck, I'm wrong almost all the time...). But it's never cool to think you are smarter than the collective scientific community of past and present....

Here, go to this website and have a look.
http://xxx.lanl.gov/
It is the first stop for all scientific publications (physical science anyway...). Do a search on dark energy and dark matter. Actually read some of the papers. Then come back and try to be more humble.

ok, ok, no need to fight.



slowly, i ambuilding up an idea of what dark matter is/could be/, however still have no idea as to what dark energy is, or the theory onto which it is based on.

as I see it, Dark matter is simply the material that, either due to its extreme lack of energy, therefore not radiating anything, and far enough from a source of energy not to reflect any of the radiation, so that we can not "see" it, or it is simply the material so far from us that we can not "see" - big universe, small telescopes...(or is it something else completly?

Dark energy, however, i still can not understand. Is it simply the energy that is being radiated away from usas oposed to towards us, eg. on the other side of our sun/galaxy etc. or is it the energy that is simply not reaching us, due to the great distences, and so defraction, or, as with dark matter, something else completly. the only cause from this that i can think up for the universe's expansion would therefore be what happens when the energy reaches the edge of the universe? i can only guess that it is this that is causing it to expand.

if this is completly the wrong enterpretation, sorry, i will study the links more carefully, if not, then thanks.

Jeremy,
In the link I gave in my previous post ( http://xxx.lanl.gov/ ) I did a search on dark matter. This was the first paper that popped up in the results;

http://xxx.lanl.gov/pdf/astro-ph/0611948

There is nothing special about this paper - it's just the first one that came up. Now... I only ask that you, Jeremy, read it. If you find that task too difficult, then just browse it. If that is too taxing, then just look at each page.


What is it that I want you to take away from this experience you may ask....

a. I would hope that you might gain a new appreciation as to the depth and detail that goes into scientific research. And mind you, I did not hand-pick this paper to find the best one to demonstrate this - it simply was the first one in the list....

b. After you grasp the level of sophistication that goes into scientific research (assuming you do...), I would further hope that you could understand why it is that comments like the one you first posted in this thread are arrogant, uncultivated, and grating.

Regards,
william

----edit----
Ah yes...you also committed a LARGE ASS appeal to authority fallacy. Just because they're scientists, doesn't mean they're "smart". Look up "appeal to authority"
----end edit----

I find it funny that your entire argument hinges on the fact they have already applied it. If you care to look deeper, they calculated it like a two body system (center and object far away).

Sure, I'll read them, not like I haven't read tons of material on it before. However let me give you some advice:

(a) don't assume you're correct
(b) don't assume scientists actually do what you expect them to
(c) Lets look at the law you cited, and inverse square law.

The gravitational attraction between two massive objects, in addition to being directly proportional to the product of their masses, is inversely proportional to the square of the distance between them; this law was first suggested by Ismael Bullialdus but put on a firm basis by Isaac Newton;

Yeah, not surprising. TWO OBJECTS. What happens when you add billions into the mix? Things become nearly incalculable. Since you know everything with your hubris manner, I suppose you wouldn't just HAPPEN to know where the calculations are for galaxy rotation are based on the gravitational pull of every star according to estimations (of how many stars there are within the galaxy, of course) would you?

No, wait, you never provided any. You ad-hom'd me and provided a law that only applies to two objects. Nowhere do I see it applied to multiple objects, especially as many as the stars in the galaxy. Plus, the equation I see on wiki is only suitable *for two objects*.

Which is what they calculated. Rather than calculating every single star (which is an obvious near-impossibility, since you'd have to know the exact mass of every star), they calculated it according to that law. Two objects. They calculated it the exact same way, with some difference, they do the solar system.

If I'm wrong in this statement, then provide their exact list of numbers they used to calculate every star in the galaxy.

What you have basically done is throw ad-hominems, act like a haughty arrogant asshole, and also committed the one thing every good scientist knows is a fallacy: assumed personality traits. Chances you are correct, based upon how you are acting, are as slim as the chances are for the sun to split in two.
Especially since you assume things so readily, rather than properly applying the scientific method.

No reasons??? Confused

Lets recap:
You mention gauss law, and invert square nexus. This doesn't suggest I'm wrong, nor suggest I'm 150 years late. Especially since inverse square law covers...*le-gasp* two objects alone! MY speculation covers the gravitational pull of the galaxy as a whole.

You also sarcastically state the following:

Good advice.

But do you really think no one has thought-of/accounted-for the objections you propose?

So when would you like your Nobel Prize?

Your maturity is about as developed as a 4 year old missing 50% of his neurons. "OOO! LOOK! HE SUGGESTS SOMETHING NEW! LETS AD-HOMINEM HIM!" The logic in your statements suggests you don't know what you are talking about. You are only parroting what you think you know.

And lets look at megabrains statemint:

Take no notice of Jeremy, and his 'BS' comment, he's just the nearest thing the forum has to flat earther...

Yes, take no notice of the fact I'm being skeptical, and take no notice of the fact megabrain has done nothing but ad-hominem my skepticisms, or utterly ignore what I'm saying.

Sufficed to say, you two are the closest the forum will get to 60 year old geneticists that scream "HEREDITY!" instead of environment and heredity. You're also about as skeptical as my cat, and trust me, that cat is the opposite of skeptical.

Your "abstract thought" has been known and taken into account for more than 150 years....

*buzzer* wrong! The law you listed, while appearing to be a screwed up attempt to just name a law, has thus far only taken into account two objects. The center, and exterior, which is how they measured the universe. They estimated the amount of gravity in the center, and it's effect on the outer (look this up, that's how they did it). Unless, y'know, the science channel is wrong.

Who told you that??? There's a fatal flaw in your "fatal flaw."
How dumb do you think the scientists are?

As dumb as they admit.

[/quote]
This was my reference to Gauss' law. Plus, the numerical modelling done using Eularian (e.g., adaptive mesh finite-difference & MHD methods) and Lagrangian (e.g., smoothed particle hydrodynamics) schemes automatically take into account all the particles of the galaxy.
[/quote]

Oh really? You only referenced Guass' law. Not the numerical modelling. However, I recall some time in the distant past where there were numerous mathematical theories were being thrown about regarding the position of the earth. Two theories were popular, and both were as mathematically likely. One suggested the earth was the center of the solar system, the other suggested otherwise.

And aside from that, how can you take into account every particle in the galaxy, when you can't count every particle in the galaxy? You can estimate, according to a lot of hypothetical guesswork, how many there are, their effects, etc. HOWEVER, particles alone are not what is most important, what is most important is large-ass gravitational bodies that reside within the galaxy.

As a side note: How can they calculate the particles in the black hole? Black holes are still messing with scientists calculations to this day, it's difficult to calculate them precisely. I've read some studies, for example, on science news websites. Much to scientists surprise, they've found black holes that are less massive than expected by previous calculations.
Honestly, assuming anything particle wise about the galaxy is extremely arrogant. While the maths behind it are impressive, arrogance is still abound.

Back to the stars: When a mass of particles is meshed together in varying gravitational extremes, there are differing effects. heavier elements are created, lighter ones are changed, etc. You basically have a furnace of differing activity, and just when you think you've calculated exactly what one star is...you have billions of others and each one is different.

Regardless, lets get back to the gravity of these stars: Show me one calculation that actually calculates what I've speculated.

If you don't explain how this works, then I won't explain how dumb this is.

Simple, since it's undetectable, who is to say that telekinetics doesn't use it? Since it's undetectable who knows!

Also, on the same note, we should be swimming in dark matter out on the galaxy's arm here. Why don't we just...I don't know...scoop some up? Yes this is kind of a blatant ignorance statement regarding how dark matter hypothetically behaves, but it sheds light on the fact that dark matter is a very large GUESS.

If this is a reference to dark energy, then you have a fundamental misconception of what it is that dark energy is supposed to explain. Try Google or Wiki.

Oh really?
http://en.wikipedia.org/wiki/Accelerating_universe

The unusual energy thought to be responsible for the acceleration is called dark energy.

Yeah...wiki just proved me correct.

N.B. It's okay to propose ideas such as the one you have. It's even okay to be wrong (heck, I'm wrong almost all the time...). But it's never cool to think you are smarter than the collective scientific community of past and present....

Define intelligence, and you may have something. However you are, once again, assuming personality traits. If I believed I was smarter than the entire scientific community, why would I even be wasting my time typing this? Use logic, not assumptions.

Then come back and try to be more humble.

Says the man who acts like he has the entire scientific community backing him!

Jeremy - do you know what Gauss's law is?

If you really want to get into the messy maths you can do asymptotic expansions for the solution so you take heavier and heavier stars into account but these are only minor adjustments to the expected rotation curve. This is because the effect of one star on another is actually quite small, since the distances between stars except near the hub is rather astronomical!

Not exactly, rat. take into account how many star clusters there are, and how much gravity we're talking about here. As a whole, it's rather massive.

Well lets do the math for the Omega Centauri globular cluster which is 5600 parsecs from earth and consists of around 7 million stars and is the largest one associated with the milky way apparently. Plugging the numbers into the newtons force law gives a total acceleration of the sun due to this huge amount of matter of around 3*10^-13m.s² which is pretty much nothing (assuming each of those stars is 10 times more massive then our sun). So even if we had a million of those clusters affecting the results then we would have a total acceleration effect in the order of 10^-7 which is about the maximum all the other planets exert on earth.

er...rat...I'm not talking about acceleration when it comes to THAT. You must've misunderstood me O.o

Or I misunderstood your message there.

I thought you were talking about the gravitational effects of the globular clusters et. al which you would handle by calculating their gravitational field and summing (which gives you acceleration of a test particle - in this case our sun - at any point in the field) over all contributions.

What exactly are you talking about?

Originally Posted by Jeremyhfht

I find it funny that your entire argument hinges on the fact they have already applied it. If you care to look deeper, they calculated it like a two body system (center and object far away).

Are you certain of this? (You may be... but you are wrong.) And who are the "they" you keep referring to? Are "they" the first scientists who attempted to calculate this some-hundred-odd years ago?

If you care to look deeper....

This is laughable coming from you....

Sure, I'll read them, not like I haven't read tons of material on it before.

Oh... you've read tons of material on this...?

However let me give you some advice:

(a) don't assume you're correct

I don't. Do you?

(b) don't assume scientists actually do what you expect them to

What is it that we expect them to do?

(c) Lets look at the law you cited, and inverse square law.

The gravitational attraction between two massive objects, in addition to being directly proportional to the product of their masses, is inversely proportional to the square of the distance between them; this law was first suggested by Ismael Bullialdus but put on a firm basis by Isaac Newton;

Yeah, not surprising. TWO OBJECTS.

That doesn't only apply to two objects. Do you think that if you introduce a third object, Newton's law of gravity fails...? Hint: superposition.

Jeremy, you have to realize that others reading this who are familiar with Newton's law of gravity are laughing their asses off....

(c) Lets look at the law you cited....

And where is the law I cited (Gauss' law)? You only state the inverse-square law....

What happens when you add billions into the mix? Things become nearly incalculable.

Which is why it's done with computer simulations.

Since you know everything with your hubris manner,

Hubris? You are the one using hubris to be so arrogant to claim that someone such as yourself can think of something so insanely simple, yet the scientific community is unable to also think of it....

I suppose you wouldn't just HAPPEN to know where the calculations are for galaxy rotation are based on the gravitational pull of every star according to estimations (of how many stars there are within the galaxy, of course) would you?

As a matter of fact, I do. Are you able to do a search on this site?!? http://xxx.lanl.gov/

No, wait, you never provided any.

Did I not say that the above link was the first stop for ALL scientific publications (physical sciences)?!?

You ad-hom'd me and provided a law that only applies to two objects.

Again, people reading this who are familiar with Newton's law of gravity are laughing their asses off....

I never ad-homed you. You truly are arrogant or else you are unable to realize that astrophysicists are also capable of recognizing the effect other stars have on each other - which is truly trivial to recognize.

And again, you are confusing Gauss' law with Newton's law of gravity. You know... there is a reason the two laws have different names....

Nowhere do I see it applied to multiple objects, especially as many as the stars in the galaxy. Plus, the equation I see on wiki is only suitable *for two objects*.

Newton's law can be applied to as many objects as you want via superposition. (I hope you didn't get an 'A' in your physics class....) Gauss' law, which you still don't understand, is a statement about which objects must be taken into account (hint: Gaussian surface). It is the same law as applied to electromagnetism, only with different terms/constants when applied to gravity. One normally first encounters Gauss' law in 3rd-semester calculus or 2nd-semester intro physics.

Which is what they calculated. Rather than calculating every single star (which is an obvious near-impossibility, since you'd have to know the exact mass of every star), they calculated it according to that law. Two objects. They calculated it the exact same way, with some difference, they do the solar system.

It is not that difficult using computer simulations. Do you need to know the exact mass of every star? No. You can use a distribution of masses to simulate a typical galaxy of your choosing. There is no need to simulate the Milky Way exactly. Indeed, that would be too much effort just to find out you get the same results going a much easier route.

If I'm wrong in this statement, then provide their exact list of numbers they used to calculate every star in the galaxy.

What a time-consuming task you are asking me to do just so you can ignore it. Again, do a search on http://xxx.lanl.gov/ and please stop referring to "them" as "they" as if this has only been done by a couple people.

What you have basically done is throw ad-hominems,

No I haven't.

...act like a haughty arrogant asshole,

Who did you say is throwing ad-hominems??? Does your new mod status now allow you to do it (I don't think so...)?

and also committed the one thing every good scientist knows is a fallacy: assumed personality traits.

You make it easy for me to assume these traits. They are almost not assumptions but fact.

Chances you are correct, based upon how you are acting, are as slim as the chances are for the sun to split in two.

Huh? Correct about exactly what? And how does the way in which one acts determine if they are correct or not? I only state with certainty that your trivial assumption that scientists haven't thought of the gravitational effect of other stars is false and complete arrogant nonsense.

By the way... you do know that I'm a physicist right? I'm not making this stuff up....

Regards,
william

so...efectivly my asumptions were...? right? wrong?...

and sorry, i didnt notice either of you mentioning anything about noing everything, but you do both seem to be childishly making up excuses to discredit one-another in a ver imature way. Just because your opinions difer, and expect logical explanations of eachother hypothoses does not mean that either are incorrect, infact, standing out against the presant accepted norm is exactly what galileo did, and was deeply discredited at the time, although eventualy prooved correc. No opinion should ever be discredited, unless hard evidance can be shown to prove ones theory correct. I beleive that many justice systems work on the idea of Guilty until proven inocent. in the same way, science works possible until proven wrong OR something else mutualy exclusive is proven correct (thus proving it wrong).

on a diferent note, it has been intresting reading about 2 diferent points of view as to dark matter, and the links, whilst a little overwelming in some places, have been of intrest.

Ohhhh brother, here we go again....
I see you edited your post I replied to. So here is my response to the rest.

Originally Posted by Jeremyhfht

----edit----
Ah yes...you also committed a LARGE ASS appeal to authority fallacy. Just because they're scientists, doesn't mean they're "smart". Look up "appeal to authority"
----end edit----

How does this work when I am a physicist myself?

Your maturity is about as developed as a 4 year old missing 50% of his neurons. "OOO! LOOK! HE SUGGESTS SOMETHING NEW! LETS AD-HOMINEM HIM!" The logic in your statements suggests you don't know what you are talking about. You are only parroting what you think you know.

Dude, I do astrophysics for a living... I hardly would call it "parroting."

Sufficed to say, you two are the closest the forum will get to 60 year old geneticists that scream "HEREDITY!" instead of environment and heredity. You're also about as skeptical as my cat, and trust me, that cat is the opposite of skeptical.

Jeremy, I simply stated that what you proposed has been thought of and accounted for long ago. Your idea was not original. This has nothing to do with scepticism. But I am a sceptic when it comes to you....

Your "abstract thought" has been known and taken into account for more than 150 years....

*buzzer* wrong! The law you listed, while appearing to be a screwed up attempt to just name a law, has thus far only taken into account two objects. The center, and exterior, which is how they measured the universe. They estimated the amount of gravity in the center, and it's effect on the outer (look this up, that's how they did it). Unless, y'know, the science channel is wrong.

Again, you must not have known that I am a physicist. And... again, you have confused Gauss with Newton. Further, while the science channel is a good place to start, if you're going to try to make arrogant scientific claims, you'll have to go to the scientific literature to see what has already been done.

This was my reference to Gauss' law. Plus, the numerical modelling done using Eularian (e.g., adaptive mesh finite-difference & MHD methods) and Lagrangian (e.g., smoothed particle hydrodynamics) schemes automatically take into account all the particles of the galaxy.

Oh really? You only referenced Guass' law. Not the numerical modelling.

I never said that I had previously referenced numerical modelling. Those are two distinct sentences you know....

However, I recall some time in the distant past where there were numerous mathematical theories were being thrown about regarding the position of the earth. Two theories were popular, and both were as mathematically likely. One suggested the earth was the center of the solar system, the other suggested otherwise.

And aside from that, how can you take into account every particle in the galaxy, when you can't count every particle in the galaxy? You can estimate, according to a lot of hypothetical guesswork, how many there are, their effects, etc. HOWEVER, particles alone are not what is most important, what is most important is large-ass gravitational bodies that reside within the galaxy.

Look up smoothed particle hydrodynamics (SPH) and see how a 'particle' is defined. In numerical-hydro lingo, 'particle' can mean atom, molecule, dust, gas, planet, star, etc.

As a side note: How can they calculate the particles in the black hole? Black holes are still messing with scientists calculations to this day, it's difficult to calculate them precisely. I've read some studies, for example, on science news websites. Much to scientists surprise, they've found black holes that are less massive than expected by previous calculations.
Honestly, assuming anything particle wise about the galaxy is extremely arrogant. While the maths behind it are impressive, arrogance is still abound.

You spout off without knowing how numerical hydro works and without attempting to learn. See my previous comment about hydro-'particles.'

Back to the stars: When a mass of particles is meshed together in varying gravitational extremes, there are differing effects. heavier elements are created, lighter ones are changed, etc. You basically have a furnace of differing activity, and just when you think you've calculated exactly what one star is...you have billions of others and each one is different.

All you need to accurately know is the star's gravitational effect, i.e., its mass. You can treat the stars as point-like particles because they are so far apart. This is how it's done for galaxy formation/evolution codes. If you don't believe me, visit that website I previously mentioned (lanl) and look it up for yourself.

Regardless, lets get back to the gravity of these stars: Show me one calculation that actually calculates what I've speculated.

You are attempting to argue like a child. The old "Oh yeah... show me then!" argument. Again, do a search on the lanl archive. You'll find more than you could possibly want.

If you don't explain how this works, then I won't explain how dumb this is.

Simple, since it's undetectable, who is to say that telekinetics doesn't use it? Since it's undetectable who knows!

This is too stupid for comment.

Also, on the same note, we should be swimming in dark matter out on the galaxy's arm here. Why don't we just...I don't know...scoop some up? Yes this is kind of a blatant ignorance statement regarding how dark matter hypothetically behaves, but it sheds light on the fact that dark matter is a very large GUESS.

There are ongoing experiments attempting to 'scoop it up.' Do a search on lanl for 'dark matter experiments' and surf around. I'm pushing the lanl site because you really need to go further than Google and Wiki....

If this is a reference to dark energy, then you have a fundamental misconception of what it is that dark energy is supposed to explain. Try Google or Wiki.

Oh really?
http://en.wikipedia.org/wiki/Accelerating_universe

The unusual energy thought to be responsible for the acceleration is called dark energy.

The acceleration of what? That's where your confusion lies.

Yeah...wiki just proved me correct.

Nope.

N.B. It's okay to propose ideas such as the one you have. It's even okay to be wrong (heck, I'm wrong almost all the time...). But it's never cool to think you are smarter than the collective scientific community of past and present....

Define intelligence, and you may have something. However you are, once again, assuming personality traits. If I believed I was smarter than the entire scientific community, why would I even be wasting my time typing this? Use logic, not assumptions.

What personality traits? You matter-of-factly claimed something in your first post in this thread and I simply said it's been accounted for. Since that time, all you have done is fire back crazy stuff and show us that you have little knowledge of physics.

Then come back and try to be more humble.

Says the man who acts like he has the entire scientific community backing him!

Nope. But I indeed do this for a living. It's fair to say that I'm a bit more 'up to speed' in these matters than you.... And more humble, because in this business, you definitely meet a lot of intelligent people to keep you that way.

Regards,
william

Originally Posted by physics student1

so...efectivly my asumptions were...? right? wrong?...

Sorry physics student1, what were your assumptions again? I'll try to answer them.

and sorry, i didnt notice either of you mentioning anything about noing everything, but you do both seem to be childishly making up excuses to discredit one-another in a ver imature way.

I'm not trying to be immature and not trying to discredit Jeremy. I'm only saying that his idea has been accounted for and it's arrogant to claim that the astrophysicists working on that problem haven't already thought of such a trivial idea.

Just because your opinions difer, and expect logical explanations of eachother hypothoses does not mean that either are incorrect, infact, standing out against the presant accepted norm is exactly what galileo did, and was deeply discredited at the time, although eventualy prooved correc.

Jeremy is not standing out. What he's saying is tantamount to someone saying "Hey, it's gravity that causes the apple to fall." It's already been done. (And in as far as what Jeremy is stating, what he states as the answer for dark matter still requires dark matter after you take what he says into account (i.e., all the stars, etc. in the galaxy).)

No opinion should ever be discredited, unless hard evidance can be shown to prove ones theory correct. I beleive that many justice systems work on the idea of Guilty until proven inocent. in the same way, science works possible until proven wrong OR something else mutualy exclusive is proven correct (thus proving it wrong).

Again, I'm not discrediting Jeremy, just stating that he's a little late. Already been accounted for... and we still need dark matter.

on a diferent note, it has been intresting reading about 2 diferent points of view as to dark matter,

Well, they are not different points of view really. Jeremy is stating that if you account for the effects of all the stars. etc. in the galaxy, there would be no need for dark matter. I'm simply saying that the stars have been accounted for and you still need something else (dark matter) to reproduce what is observed.

...and the links, whilst a little overwelming in some places, have been of intrest.

The one link that was overwhelming was simply to point out to Jeremy that scientists are not as dumb as he thinks they are.... That particular link would be overwhelming to anyone who is not already an expert in that particular field of research.

Cheers,
william

Originally Posted by william

Are you certain of this? (You may be... but you are wrong.) And who are the "they" you keep referring to? Are "they" the first scientists who attempted to calculate this some-hundred-odd years ago?

The "they" is a vague reference to some mythical organization that represents dark matter. It's only for clarity purposes, nothing more.

This is laughable coming from you....

...okay, you know what, if childish comments like this continue from you I have no further inscentive to continue.

Oh... you've read tons of material on this...?

I've never quite seen someone so determined to attack a person directly rather than attack their ideas. If this continues I'll have to bring an administrator in to settle it. This forum does have rules regarding behavior to other members.

That doesn't only apply to two objects. Do you think that if you introduce a third object, Newton's law of gravity fails...? Hint: superposition.

Wow, I've never quite seen someone so blindly arrogant they utterly ignore the message something conveys. You, sir, win a prize.

Allow me to shed some light: Newton's law of gravity doesn't fail. Newtons law has, so far, proven accurate. However, I'm suggesting they are applying it improperly by assuming a two-body application. The massive gravitational pull in the center, and the arms that extend outwards of the galaxy. I've yet to see someone explain a computer simulation and say "this was originally calculated by judging the overall gravitational pull every star has on other stars."

Jeremy, you have to realize that others reading this who are familiar with Newton's law of gravity are laughing their asses off....

You have to realize that you apparently have no idea what I'm talking about. And once again, you apparently are more focused on what other people think than what is going on in this discussion. Your ad-hominem tactics are getting old. As a moderator, I ask you to tone it down. And as a forum user, I'm telling you it's getting old.

And where is the law I cited (Gauss' law)? You only state the inverse-square law....

Lets quote wiki:

Gauss's law can be used in any context where the inverse-square law holds,

Now you know why I did it.

Which is why it's done with computer simulations.

Provide a source that actually shows they've done a computer simulation based on the gravitational pull of each individual star (including black holes in the galaxy)? In order to calculate the incalculable you have to know every variable. I highly doubt anybody knows that much information about the galaxy. At best, it's hypothetical guesswork by using numerous physical laws, and it isn't perfectly accurate.

The obvious and most shallow counter argument to this is "of course it isn't perfectly accurate, but it's still accurate to an extent."
Unfortunately one has to assume this, one can't exactly calculate the exact mass of every star in the universe, since every star in the universe can't be calculated.

Hubris? You are the one using hubris to be so arrogant to claim that someone such as yourself can think of something so insanely simple, yet the scientific community is unable to also think of it....

Now this is where straw man tactics are used. Did I say the scientific community is unable to think of it? No. Did I say that they're applying the current laws improperly? Yes. However it isn't unlikely for mainstream scientists to have overlooked the simplistic. That is a probability that must be taken into account.

However judging by your statement: It's apparently a hubris act to speculate that which one doesn't believe is currently used. I presently have not received even one computer simulation model that attempts to form a galaxy according to my speculation above.
If one exists, point the way.

As a matter of fact, I do. Are you able to do a search on this site?!? http://xxx.lanl.gov/

...and? Where is it? I'm not going to search through tons of articles in hopes I find something that agrees with everything else. You basically throw the link out there and say: "If you can somehow find an article that does so, and provides a computer simulation that failed with a detailed explanation, then you are wrong. However I wont provide you with a direct link, since I can't find it either"

Did I not say that the above link was the first stop for ALL scientific publications (physical sciences)?!?

So...you want me to spend hours or days reading through countless amounts of material in hopes I find what I'm looking for? Yeah...that is such a debatable link...

Again, people reading this who are familiar with Newton's law of gravity are laughing their asses off....

Right...while they're laughing their asses off, let them turn to what the computer simulations are doing. Then they can laugh their asses off at their own mistake.

I never ad-homed you. You truly are arrogant or else you are unable to realize that astrophysicists are also capable of recognizing the effect other stars have on each other - which is truly trivial to recognize.

So basically, they can count every star in the galaxy, figure out how many possibly undetectable black holes there are, figure out how much mass those black holes have, and numerous other figures that require physical information that we currently do not have. Right. I'll believe that if you'd ever provide a direct source.

and yes, you have. From now on I will paste the following whenever you do so, in hopes it'll be pounded into your skull:

An ad hominem argument, also known as argumentum ad hominem (Latin, literally argument against the person), personal attack or you-too argument, involves replying to an argument or assertion by attacking the person presenting the argument or assertion rather than the argument itself. It is a logical fallacy.

And again, you are confusing Newton's law of gravity with Gauss' law. You know... there is a reason the two laws have different names....

Where have I done so?

Newton's law can be applied to as many objects as you want via superposition.

Assuming all those objects have the exact same prosperities as the original object in question. Otherwise you have to add exact variables for every new object included. Obviously scientists don't do that.

(I hope you didn't get an 'A' in your physics class....)

An ad hominem argument, also known as argumentum ad hominem (Latin, literally argument against the person), personal attack or you-too argument, involves replying to an argument or assertion by attacking the person presenting the argument or assertion rather than the argument itself. It is a logical fallacy.

Gauss' law, which you still don't understand, is a statement about which objects must be taken into account (hint: Gaussian surface). It is the same law as applied to electromagnetism, only with different terms/constants when applied to gravity. One normally first encounters Gauss' law in 3rd-semester calculus or 2nd-semester intro physics.

I skipped over gauss law and went straight to inverse square law.

It is not that difficult using computer simulations. Do you need to know the exact mass of every star? No. You can use a distribution of masses to simulate a typical galaxy of your choosing. There is no need to simulate the Milky Way exactly. Indeed, that would be too much effort just to find out you get the same results going a much easier route.

...and?

What a time-consuming task you are asking me to do just so you can ignore it. Again, do a search on http://xxx.lanl.gov/ and please stop referring to "them" as "they" as if this has only been done by a couple people.

I explained the "they" bit above.
Once again, you expect me to comb through tons of written work to find exactly what I'm looking for. No matter how well worded the search criteria is, I doubt it's a feasible task.

...act like a haughty arrogant asshole,

Who did you say is throwing ad-hominems??? Does your new mod status now allow you to do it (I don't think so...)?

...of all the stupid reporter-style out of context quotations I've never seen one that bad. Lets try to explain, since it apparently flew over your head, the context:

What you have basically done is throw ad-hominems, act like a haughty arrogant asshole,

In context, I make reference to your attitude about the debate so far. The fallacy is attacking a person rather than the logic of their argument. In context, this isn't attacking you in favor of the argument, this is an entirely different statement questioning your behavior thus far.

Ah yes, and a cheap-jab with a moderator comment...that isn't even worth a reply. I'll ignore the rest, since it's getting far enough off topic as it is.

By the way... you do know that I'm a physicist right? I'm not making this stuff up....

Appeal to authority fallacy, once again.

An appeal to authority or argument by authority is a type of argument in logic, consisting on basing the truth value of an otherwise unsupported assertion on the authority

I don't care if you are the king of Siam.

Dude, I do astrophysics for a living... I hardly would call it "parroting."

An appeal to authority or argument by authority is a type of argument in logic, consisting on basing the truth value of an otherwise unsupported assertion on the authority

Jeremy, I simply stated that what you proposed has been thought of and accounted for long ago. Your idea was not original. This has nothing to do with scepticism. But I am a sceptic when it comes to you....

If it has been applied already, where are the computer simulations that failed to do so? Once again, I repeat, the only ones I've read about go on a two-body fallacy. The center and the outer.

Again, you must not have known that I am a physicist.

An appeal to authority or argument by authority is a type of argument in logic, consisting on basing the truth value of an otherwise unsupported assertion on the authority

And... again, you have confused Newton with Gauss.

Where have I done so? If you are going to claim something, do so directly.

In numerical-hydro lingo, 'particle' can mean atom, molecule, dust, gas, planet, star, etc.

...need I say anything?

You spout off without knowing how numerical hydro works and without attempting to learn. See my previous comment about hydro-'particles.'

...and this voids my argument here? Not really, more like avoids.

All you need to accurately know is the star's gravitational effect, i.e., its mass. You can treat the stars as point-like particles because they are so far apart. This is how it's done for galaxy formation/evolution codes. If you don't believe me, visit that website I previously mentioned (lanl) and look it up for yourself.

Not all stars are far apart, and it isn't just stars. You are apparently excluding the gigantic black hole that's sitting nice and pretty in the center of the galaxy. And a stars gravitational effect, depending on size and placement, is more than a point-like particle (and in some cases less), you can't make that generalization accurately.

You are attempting to argue like a child. The old "Oh yeah... show me then!" argument. Again, do a search on the lanl archive. You'll find more than you could possibly want.

...again, search for what? Since you OBVIOUSLY know they exist, you should've provided a keyword since you OBVIOUSLY searched for them before.

And I didn't know that wanting evidence for something was arguing like a child. Gee, I guess science is childlike.

There are ongoing experiments attempting to 'scoop it up.' Do a search on lanl for 'dark matter experiments' and surf around. I'm pushing the lanl site because you really need to go further than Google and Wiki....

I know, of numerous experiments being conducted. Including some in mines. Each one has failed...and failed...and failed...and failed....aaaaaaaannnnndddd failed more. Sure, perhaps one day they may succeed, but that's optimistic at best. Let me reformulate the question to get a ball rolling: why can't we scoop some up? Since dark matter obviously effects everything, why can't we detect this all-effecting dark matter?

The acceleration of what? That's where your confusion lies.

Er...I'm speaking of the acceleration of galaxies. Ergo, our universe. which is exactly what the link explains. I think that's where your confusion lied, you misunderstood.

What personality traits? You matter-of-factly claimed something in your first post in this thread and I simply said it's been accounted for. Since that time, all you have done is fire back crazy stuff and show us that you have little knowledge of physics.

...nnngh...once again, you attack me personally rather than my ideas. And on the basis of intelligence, which is relevant to the ideas. In-context: Ad hominem.

Nope. But I indeed do this for a living. It's fair to say that I'm a bit more 'up to speed' in these matters than you.... And more humble, because in this business, you definitely meet a lot of intelligent people to keep you that way.

Regards,
william

An appeal to authority or argument by authority is a type of argument in logic, consisting on basing the truth value of an otherwise unsupported assertion on the authority, knowledge or position of the person asserting it.

Originally Posted by William

I'm not trying to be immature and not trying to discredit Jeremy. I'm only saying that his idea has been accounted for and it's arrogant to claim that the astrophysicists working on that problem haven't already thought of such a trivial idea.

You're "only" saying that I'm an idiot, that my suggestion is so simplistic it has to have been done before, that I'm arrogant for suggesting it has not, and you're also saying that because you hold the title of "physicist" you automagically know all there is (See: Appeal to authority).

Jeremy is not standing out. What he's saying is tantamount to someone saying "Hey, it's gravity that causes the apple to fall." It's already been done. (And in as far as what Jeremy is stating, what he states as the answer for dark matter still requires dark matter after you take what he says into account (i.e., all the stars, etc. in the galaxy).)

...WTF? Again, I want to see a computer simulation that does what I hypothesized and failed. You keep giving that same link, and telling me to search, but again...search for _what_? I could use a few hundred different keywords and still not get the one I want.

Again, I'm not discrediting Jeremy, just stating that he's a little late. Already been accounted for... and we still need dark matter.

So...assuming personality traits, using ad-hominems to discredit my statements, using an appeal to authority fallacy to elevate yourself, etc, isn't discrediting? I give up. GIVE. UP.

Well, they are not different points of view really. Jeremy is stating that if you account for the effects of all the stars. etc. in the galaxy, there would be no need for dark matter. I'm simply saying that the stars have been accounted for and you still need something else (dark matter) to reproduce what is observed.

And I'm now asking for proof of that claim. Once again, I've never seen a computer simulation mentioned that does so properly.

[quote]
The one link that was overwhelming was simply to point out to Jeremy that scientists are not as dumb as he thinks they are.... That particular link would be overwhelming to anyone who is not already an expert in that particular field of research.
[quote]

.....

Jeremy, you haven't read my replies carefully in regards to the ideas. I think you concentrate more on looking for ad-hominems and personal stuff.

I explained why it is not necessary to know every star, black hole, etc. in the Milky Way exactly in order to simulate it. You glossed over that as if it wasn't there.

You still have confusion as to what it is that dark energy is supposed to explain. Your 'appeal to authority' (Wiki) (which you accuse me of...) doesn't seem to clarify it for you.

Since you refuse to teach yourself Gauss' law, it simply states (in more mathematical terms...) that only the mass inside a Gaussian surface affects a mass on or outside that Gaussian surface. This means that you only need to account for the mass within a Gaussian surface at the 'radius' where the star is at. Wiki 'Gaussian surface' and know (though they don't state it) that there is a gravitational analogue.

But that's besides the point, the numerical simulations automatically account for every 'particle' in the system, whether it's affected by another particle (inside the GS) or not (outside the GS).

As to your careless dismissal of what a 'particle' represents in hydro codes, you simply need to read up on these simulations and learn how they work. (Real reading - Wiki and Google will not suffice here....)

As to your statement that not all stars are far enough apart to represent them as point-like particles, again, you need to do some further reading on how the codes work. I have to appeal to the literature because no matter what I say, you wouldn't take my word for it anyway....

You dismiss my attempts to explain how the calculations are done. Re-read what I said carefully. And note, there are people knowledgeable in math and physics in this forum (e.g., River_Rat, mitchellmckain, Guitarist). If I am wrong, surely someone else (other than you) will come along and correct me.

My asking you for a search for galactic simulations on the lanl site is not an overwhelming one. Almost any (if not every) paper on galaxy evolution/formation/etc. simulations will explain how they do it. Just pick one. That's what I'm saying. Almost all (if not all) take what you suggest into account!

You are choosing to take what I say personally. I'm not attacking your character by saying things like you don't know much about physics. Someone can say about me that I don't know much about cooking.

Finally:

Originally Posted by Jeremyhfht

I've never quite seen someone so determined to attack a person directly rather than attack their ideas. If this continues I'll have to bring an administrator in to settle it. This forum does have rules regarding behavior to other members.
.
.
.
Your ad-hominem tactics are getting old. As a moderator, I ask you to tone it down. And as a forum user, I'm telling you it's getting old.

Jeremy, I maintain that I am not attacking you personally. In fact, I feel that it is you who is acting immature and attacking me (and I think we both know why... it has something to do with a PM I sent you a few days ago...). But... since you are threatening me, and indirectly using your moderator status as a threat, I have lost the will to continue this stupid discussion with you.

Besides, I've pretty much said all that I can say in regards to your objections. Those who read this and have the mathematical/scientific knowledge will be able to discern if I am correct or not.

One last thing.............
I enjoy this forum, made a few friends, and I hope that I can stick around. But if you, as a moderator, are going to take out a personal vendetta against me, then go to hell. I couldn't care less if you are a mod or not. Ban me if you're that immature, but I am not going to take your crap.

Now leave me alone....

william

Sparticles are good candidates for dark matter, They would be massive particles that don't interact with "normal" matter, so wouldn't be detectable by conventional means.

Idea to expanding universe, dark energy.

Space versus Volume


Showing a comparison between changes in space and volume:


We start with a cube:
The cube has 10cm length * 10cm height * 10cm width

We place in one sphere with diameter 2.67cm and volume inside the box. Then we add volumes of spheres together; as in water dropplets that merge as one.

The below is: box width (x axis) minus sphere diameter(d#).

(x)10cm - 2.67cm(d1) = 7.33cm total distance from walls x axis for volume

add another 2.67cm diameter sphere
10cm - 3.37cm = 6.63cm total distance from walls x axis for volume

add one more 2.67cm diameter spheres
10cm - 3.86 cm = 6.14cm total distance from walls x axis for volume

add one more 2.67cm diameter spheres
10cm - 4.24cm = 5.76cm total distance from walls x axis for volume

add one more 2.67cm diameter spheres
10cm - 4.57cm = 5.43cm total distance from walls x axis for volume

As we see the volume increases as expected but, the axis space does not increase the same way. They change by different ratio's.

The following is, the distance total to the walls, relative to the diameter of the sphere, as we added spheres.

7.33cm to 6.63cm to 6.14cm to 5.76cm to 5.43
>
7.33cm - 0.7 = 6.63cm - 0.49 = 6.14cm - 0.38 = 5.76 - 0.33 = 5.43
>
0.7 , 0.49, 0.38, 0.33
>
0.7/0.49=0.7
0.38 / 0.49 =0.77
0.38 / 0.33 = 0.86

We see the distance of, in this case axis "x, changes by a different ratio than volume. This difference is that distances increase faster than does volume.

There are ratios here that can be calculated but it is something I would need help to calculate.

Volume increases at a constant ratio. That is, if you add to a given volume you gain to the total.

Conclusion:

This concludes that space increases differently than volume. The result of this is that, space or distance between posistions (of 1D one axis), changes at a different ratio than does the volume of bodies.

This is supporting the fact space will be observed to acclerate in expansion as matter collects and form individual bodies.

*If this ratio is correctly calculated, it should predict an accurate value of expansion of the universe, in relation to the observed average volume of matter, for a given observed zone.