Thread: Dark Matter!

I was reading various articles in which points to the existance of 'dark matter'. I've been having trouble fathoming equations. I just like talking about the universe and enjoying everyone's shared-facts and opinions. I think I would like to hear what the people have to say, other than me.

So, what do you know about Dark Matter, Dark Energy, the Cosmological Constant(Einsteins Biggest Blunder), Red-Shifts of Super-Novas leading to the conclusion of universal expansion, and the possibility of anti-gravity?

Well, you don’t ask much (sarcasm off). :wink:
Briefly, I know that the observed spin speed of galaxies would cause them to simply fly apart unless more mass was in them than can be accounted for by what can be seen. The unseen “dark” mass was either in MAssive Compact Halo ObjectS (MACHOS) (like blackholes) or in a huge cloud of subatomic Weakly Interactive Massive ParticleS (WIMPS). In this case the WIMPS won and we are trying to find a way to image evidence of their existence (possibly with the Large Hadron Collider).
Observations of light from distant Supernovae indicated that they were dimmer than they should be according to their redshift. One way that would account for this is that the universe was not only expanding at a given rate, but that the expansion was actually accelerating. If you take the mass of the energy and matter in the universe and factor in the observed acceleration, then the unseen or “Dark Energy” necessary to account for this acceleration is revealed.
Einstein’s “Biggest Blunder” was perhaps doubting his correct use of a Cosmological Constant to counter the effect of the General Theory of Relativity and keep the observed universe from collapsing back into a singularity. It probably cost him a(nother) Nobel Prize.
The Dark Energy is an inflationary force that stretches space time. If it continues to grow without any natural barrier, then it will overcome local gravity and the strong force in our atoms and the Big Rip will take place in about 22 billion years.

Hmmm ... :-D

I am new at all this :? Just to be sociable ... here is my two cents.

I know that dark matter and dark energy are two different things.

Dark energy or the cosmological constant is an energey density that does not dilute as the universe expands. Our current expansion of the universe is influenced but not complete so by dark energy. There is also a matter density factored into the FRW equations. Matter density dilutes as the universe expands and so we are approaching a point in history where the effects of matter are becoming less significant. We are approaching exponential expansion.

Dark matter are particles not yet detected in particle accelerators but whose presence has been summised by measuring the velocity of rotation in galaxies.

I'll stop now before saying something dumb.

MB ...

Personally, I agree with you both, it is true that the universe is expanding, and from studies based on our 'standard candles' (type 1a super novea), the universe is indeed speeding up. From all that- I've made a theory. If you'd like to know what it is, read on.

Think of positronium for a moment. Picture the [edit] electron [/edit] and it's anti-particle, positron, meeting in space-time and starting to revolve around each other. As they continue their revolutions, they give off photonic energy in wave-function form. The closer these two particles seem to become, the stronger the photonical wave functions start to become. Now they collide; a large burst of energy is emited and the vision is over.

How this relates?

I believe that something 'similar' to positronium is in existance; something far more massive, and far more powerful- so powerful, gravity can not overcome it. I'll name this object, COMB, just for identitive purposes. The COMB are two massive objects now, revolving around each other, giving off energy, increasingly over time until COMB eventually collides giving off what everyone believes to be the 'big bang'. I believe to be this energy is indeed the 'dark energy' and is pushing this 'dark matter' previously created by, I don't know- possibly a previous repetition of COMB.

The point however, is that if this COMB is indeed the reason behind the inceasingly speeded-up expansion of the universe, the big bang didn't even happen yet, or it did, and the universe indefinitely repeats this cycle.

I don't see many flaws in this, since I do not read as much as I think; pointing me to contradicting articles, or even just explaining would never be frowned upon. I like opposition. And thank you Arch2008, because I'm not very good at noticing sarcasm via internet. lol

Originally Posted by IOPTFEAR

The point however, is that if this COMB is indeed the reason behind the inceasingly speeded-up expansion of the universe, the big bang didn't even happen yet, or it did, and the universe indefinitely repeats this cycle.

I don't see many flaws in this, since I do not read as much as I think; pointing me to contradicting articles, or even just explaining would never be frowned upon.

I think, you are not properly considering the assumptions you make, when you put forward such an idea. Since the hypothetical Big Bang is thought of having produced space itself, how could there have been particles revolving around each other? Isn't this a contradiction? I also think that you believe that the so called Big Bang was an explosion within an already existing entity. This is wrong. The order of cause and effect is actually reversed. First came the expansion. And since the universe was so small, the temperature was very high. So, it was not a hot explosion that started the expansion, it was the initial generation of space and its expansion that made room for the matter - naturally being very hot - and since then drags it along while it is expanding. The force causing the expansion is still unknown and is commonly referred to as Dark Energy, a term I really don't like. It easily produces preconceptions about its nature. "Dark" only means, we don't know, what it is.

Dark matter was never actually observed. All results are only indirectly measuring a phenomenon that could be explained by additional matter. From my perspective, I am not convinced that Dark Matter actually exists. There are other possibilities being followed up to explain the phenomena in a different way.

Yes, I do have a different perspective of the big bang. I don't believe the universe came from nothing. I believe in the conservation of matter/mass. The belief of a 'singularity' is just as preconceptional as 'dark matter' or 'dark energy', so I guess we're both in a pickle there; my theory of the big bang however isn't really the big bang everyone thinks about, but instead if something was powerful enough to push galaxies, and was in a process similar to positronium, the explosion would be either as great or greater than the explosion expected in the theory of the big bang itself.

Now, for the begining of time, if this 'singularity' existed and everything came from one infinitesimally small, infinitely hot, inifinitely dense point, then of course it's pressure would push outward creating space, simualtaneously expanding, and creating what we now call the universe. What I think though, is how did this 'singularity' come into existance- basically, how did all that matter actually get there? That's why I bring into perspective a new view upon the 'big bang'. I think it's not a singularity that expanded; maybe an expansion that's accelerating due to a force created by an act of an infinitely repeating process- like a galactic, analigical form of positronium.

I don't know man, I think my theory fits pretty well, but I'm still listening.

Originally Posted by IOPTFEAR

The belief of a 'singularity' is just as preconceptional as 'dark matter' or 'dark energy', so I guess we're both in a pickle there.

While singularities, dark matter, and dark energy are speculative, black holes are certainly known to exist. And something must be driving the forces behind the event horizon, just as I suspect there are forces other than dark energy / matter fueling the accelerating expansion of the universe.

Spagettification is the proximity effects of black holes' gravity; meaning, the closer u get, the stronger its attraction. If one was to dive into a black hole, the head would fall faster than the feet, causing the body to be stretched. Relative to the bellybutton, both the head and feet pull away at an accelerating rate.

Spagettification = Accelerating Expansion

Galaxies moving away from us at an accelerating rate is indeed evidence of some sort, just not of an expanding universe. I propose the exact opposite: collapsing into a black hole of epic proportions. This model fits with our observable universe (especially redshift) without the need of concocting the fantastic repelling properties of dark matter / energy. Furthermore, it directly addresses Einstein's Cosmological Constant.

There are many more implications from this model; wrap your heads around the aforementioned first.[/b]

Originally Posted by IOPTFEAR

So, what do you know about Dark Matter, Dark Energy, the Cosmological Constant(Einsteins Biggest Blunder), Red-Shifts of Super-Novas leading to the conclusion of universal expansion, and the possibility of anti-gravity?

An immense array of protons perhaps surrounding a galaxy would be so well spaced out that the distributed mass would be its only conspicuous manifestation. Just like dark matter.

If the universe held a significant negative charge, bodies matching such charge would temporarily accelerate toward the cosmic outer limits just to get away from the crowd. A small example of such behavior is represented on earth whereby electrons hustle toward the so-called ionosphere. Their motion comes about after a dead stop, so acceleration is part of such migration, but this does not reflect upon the integrity of our gravity.

Dark matter is based on the perceived speed of rotation in a galaxy. However if the redshift has another factor involved, as in gravitational drag from all matter in the galaxy redshifting it further, then stars are moving slower than thought, so no need for DM. DM however has a number of serious problems wrong with it, notably that it only reacts as wanted and not as it would naturally do if as claimed.

Dark energy is an idea. It is essentially an anti gravity energy, a "repulsive force", which only decades earlier scientists said was impossible. The idea is needed to explain an apparent acceleration in the expansion of the universe several billion years ago.

Type1A supernovae are said to be standard candles (ie: always the same, as near as matters), so distance could be accurately gauged. However a few years back one was discovered twice as bright as it should be and this was simply because it was rotating faster. There are a number of other factors in such a supernova or in the surrounding medium which can cause them to be brighter or darker, so not the standard candle it was thought they were.

As to redshifts, we essentially live in a snapshot of the universe since any movement of galaxies takes place over cosmic time so we will never see them move in expansion as many believe they do. While photons can continue for billions of years, it is still debatable whether gravity can do the same despite the fact that we know very distant objects can exert a pull on our galaxy (like the wall of galaxies), etc. If photons have a continuous gravitational drag on them as they travel, then they will further redshift on top of any recessional redshift, so leaving that as a measure of distance and not of speed of recession.

Originally Posted by Cyberia

Type1A supernovae are said to be standard candles (ie: always the same, as near as matters), so distance could be accurately gauged. However a few years back one was discovered twice as bright as it should be and this was simply because it was rotating faster. There are a number of other factors in such a supernova or in the surrounding medium which can cause them to be brighter or darker, so not the standard candle it was thought they were.

Indeed. There may be another problem with the influence of heavy elements (or metals as astronomers call them - everything that is heavier than helium - silly, isn't it) that were much less abundant in earlier epochs of the universe. The abundance of such elements could influence the characteristics of a Type Ia supernova outburst. This would introduce another variable that is depending on lookback time, i.e. distance.

Originally Posted by 6nqpnw

Spagettification is the proximity effects of black holes' gravity; meaning, the closer u get, the stronger its attraction. If one was to dive into a black hole, the head would fall faster than the feet, causing the body to be stretched. Relative to the bellybutton, both the head and feet pull away at an accelerating rate.

Spagettification = Accelerating Expansion

Galaxies moving away from us at an accelerating rate is indeed evidence of some sort, just not of an expanding universe. I propose the exact opposite: collapsing into a black hole of epic proportions. This model fits with our observable universe (especially redshift) without the need of concocting the fantastic repelling properties of dark matter / energy. Furthermore, it directly addresses Einstein's Cosmological Constant.

There are many more implications from this model; wrap your heads around the aforementioned first.[/b]

It doesn't work. The spaghettification only acts along the line that you are falling in.

Thus you would see the greatest redshifts when you look at galaxies that lie directly away from or towards the black hole and zero redshift (or even a small blue-shift) when you look at galaxies at a right angle to that line.( These galaxies are the same distance from the Black hole as you are and are neither falling faster or slower than you are, and if anything are falling along a convergent path to yours and are getting closer. )
Not only that, but even looking in or out would not give the same Doppler shift. Light coming out from the black hole will undergo a gravitational red-shift, and light falling in will show a gravitational blue-shift. Thus two galaxies an equal distance from you, but in opposite sides of the sky, would show different shifts.

This is not what we see. No matter what direction we look the red-shift is the same for galaxies of equal distance.