Dark Matter

[Patronus]

[size=1]Alright, this is something very interesting that I learned in CP Science today.

In Space, there is supposedly this unseen force called dark matter. It relates directly to the Big Bang Theory, but unlike the Big Bang Theory, it [i]has[/i] been proven. Scientists have only seen the effects of dark matter, but not the force itself.

Dark matter is one of the forces that is moving the stars, galaxies, and everything else [i]outward[/i] in the universe. This is another relation to the Big Bang Theory, as scientists have said that even though the Big Bang happened billions of years ago, it's still in effect. We are always moving in an outwards direction, and it has been proven.

The point of this thread is to get your opinion on what dark matter is, or what it's a result of.[/size] [b]I plead you not to let this turn into a religious thread, as that is not what I want it to be.[/b]

[size=1]Oh, and I have more information on this, in my notes, but I don't have them with me, so I'll post them tomorrow. ^_~

EDIT: Here, I found a good article that explains more of dark matter. I'll still post my notes later.

[quote]
[b]Dark Matter Mystery[/b]

While carefully measuring the speed of rotation of galaxies, astronomers stumbled upon a profound cosmic mystery.

They could estimate what the rotation speed should be by calculating the mass of all the visible stars and gas, thereby determining the gravity of the galaxy. Much to their surprise, the measurements showed that most galaxies are rotating faster than they should. Not a little faster. Much faster! More than twice as fast. This meant that, according to Einstein's theory of gravity, these galaxies should be flying apart. Yet clearly, they are not.

What can the answer be? Is it possible that most galaxies are surrounded by some "dark" form of matter that cannot be observed by radio, infrared, optical, ultraviolet, X-ray, or gamma-ray telescopes? Could Einstein's theory of gravity, which has proved to be correct in all cases so far, be somehow wrong?

X-ray telescopes have discovered vast clouds of multimillion degree gas in clusters of galaxies. These hot gas clouds increase the mass of the cluster, but not enough to solve the mystery. In fact they provide an independent measurement of dark matter. The measurement shows that there must be at least four times as much dark matter as all the stars and gas we observe, or the hot gas would escape the cluster.

[i]What can the dark matter be?[/i]

Scientists are considering a number of possibilities. Candidates for dark matter include MACHOS, WIMPS and GAS. A "Good News" and "Bad News" analysis is given below for each of the candidates.

MACHOS (Massive Compact Halo Objects) Examples: brown dwarfs, white dwarfs, neutron stars, black holes.

Brown Dwarf stars have a mass that is less than eight percent of the mass of the Sun--too low to produce the nuclear reactions that make stars shine.

[b]Good News[/b]: Recently, astronomers have found some objects that are either brown dwarf stars or very large planets around other stars. Observations of the brightening and then dimming of distant stars--thought to be due to the gravitational lens effect of a foreground star-- may also provide further evidence for a large population of brown dwarfs in our galaxy.


[b]Bad News[/b]: There is as yet no evidence that brown dwarfs are anywhere near as abundant as they would have to be to account for the dark matter in our galaxy.


White Dwarfs are the final condensed states of small to medium sized stars.

[b]Good News[/b]: White dwarfs are known to exist and to be plentiful. Maybe they could be plentiful enough to explain the dark matter if young galaxies produced white dwarfs that cool more rapidly than present theory predicts.


[b]Bad News[/b]: No good alternative to the present theory exists. Also the production of large numbers of white dwarfs implies the production of a large amount of helium, which is not observed.


Neutron Stars or Black Holes are the final condensed states of large and very large stars.

[b]Good News[/b]: They can be dark, especially black holes, which are totally dark, except for a negligible amount of so-called Hawking radiation. See [url]http://chandra.harvard.edu/resources/faq/black_hole/bhole-31.html[/url]


[b]Bad News[/b]: These objects are expected to be much scarcer than white dwarfs. Also, the processes that produce these objects release a lot of energy and heavy elements; there is no evidence of such a release.

WIMPS (Weakly Interacting Massive Particles) Examples: Exotic Subatomic Particles such as axions, massive neutrinos, and photinos.

[b]Good News[/b]: Theoretically, WIMPS could have been produced in the Big Bang origin of the universe in the right amounts and with the right properties to explain the dark matter.


[b]Bad News[/b]: No one has ever observed even one of these particles, let alone enough of them to explain the dark matter.


Hydrogen Gas

[b]Good News[/b]: Seventy to seventy-five percent of the visible matter in the universe is in the form of hydrogen, the simplest element. It may be possible that the dark matter is numerous small clouds of hydrogen gas.


[b]Bad News[/b]: It is very difficult to hide hydrogen gas from the probing, sensitive eyes of radio, infrared, optical, ultraviolet, and X-ray telescopes.[/quote][/size]

[Semjaza]

All I know about Dark Matter comes from Futurama... and apparently they're nothing alike. Dark Matter is used for starship fuel and Leela's pet, Nibbler, craps it out. Each pound of it weighs precisely 10,000 pounds according to the Professor.

Anyway, I don't know much about the real Dark Matter. I can see how the idea of the universe moving outwards could be proven, but how can they prove the existance of dark matter itself if it's based on the big bang, which is just a theory? Theories based on theories seem rather arbitrary heh.

Edit -- You added some article right after I submitted my post, so I'll have to read it heh. From your post alone, the idea of it didn't make much sense lol.

[Dragon Warrior]

Yeah, I've heard of Dark Matter before. My science teacher mentioned it so I asked him what it was and he told me. I find it very fascinating and was thinking of writing some kind of story or whatnot on it. It's strange what's out there beyond us :)

[Patronus]

[size=1]Hey, I've got the notes. Please, if there are some mistakes or something, forgive me. My teacher doesn't know how to type notes. >.>

[quote]One of the main goals of many astronomers is to solve the mystery of the origin of the universe. The universe is everything that exists, including all matter and energy everywhere. Scienteists do not know the answer to the questions "How did the universe begin?" or "If stars go through cycles, does the entiore universe also go through some type of cycle?", but they have gather enough information to formulate a theory. This theory is based on evidence that the size of the universe is not constant, but is expanding.

If galaxies are moving apart, then preumably they used to be closer together. Moving backward in time to what scientists refer to as "time zero", somewhere between 10 and 15 billion years ago. At that time, all the matter in the universe was packed together into one small, extremely dense, hot mass under enormous presure. This very hot, tightly compacted matter exploded which sent energy in all directions. As it expanded, it ultimately became clumpy as matter condensed into stars and galaxies which formed our present day Solar System. Therefore, scientists use the [b]Big Bang Theory[/b] to describe the beginning of the universe that emerged from this start of enormous density and temperature. According to Einstein's general relativity theory, the Big Bang event was the creation of matter, energy, space, and time.

Although the Big Bang theory is widely accepted by scientists, it probably will never be proven. The theory was initially suggested because it explains why distant galaxies are traveling from us at great speeds. This is exactly the pattern that would occur if the entire universe originated in a single explosion -- the Big Bang.

[b]Support for the theory include[/b]:

1. As galaxies continue to move away from us, they stretch the wavelength of the light coming from other galazies. Therefore, the light from distant galaxies is shirted toward the red (long wavelength) end of the visible spectrum. So "redshift" is a measure of how far away galaxies are.

2. Redshift serves as a clock, too. The light from other galaxies takes longer to reach us the further away they are. So when we look at high-redshift galaxies, we are looking far back in time, seeing the universe as it was billions of years ago.

3. The theory received its strongest confirmation when scientist Arno Penzias and Robert Wilson, discvoered the existance of cosmic background radiation (the glow left over from the explosion istelf). They detected microwaves coming from all directions in the sky.

[b]Dark Matter[/b]
-composes much of the universe.
-cosmic radiation caused by [u]dark matter[/u].
-it is radiation released when atoms formed.
-it is a msterious [u]unseen[/u] force of matter.
-astronomers attribute it with the increasing rate of expansion of the universe.[/quote]

Yeah, I know there's some maybe unneeded information, but reckoned I'd throw it in for some background. ^_~[/size]

[Gavin]

[size=1]Like Dragon Warrior, I've been told a relatively small amount about Dark Matter by my science teacher in secondary school (similar to High School). It's very interesting to be able to read about it in greater depth and how it may give rise to new theories about the movement of galaxies and the plausablity of the [b]Big Bang[/b] theory.[/size]