The Dark Matter Mystery: Stars Are Moving Too Fast

http://www.facebook.com/ScienceReason ... The Mystery of Dark Matter (Chapter 1/4): Stars Are Moving Too Fast.

A mystery exists! Galaxies do not seem to have enough mass for stars to orbit at their observed speeds. Galaxies should be flying apart, but they don't. Why not? Explore the surreal world of dark matter - one of the universe's greatest mysteries.

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Shedding Light on Dark Matter

Over the last few decades, physicists have discovered that around ninety percent of every galaxy in the universe is made of an unseen substance called dark matter. Damian Pope, PIs Senior Manager of Scientific Outreach, comments, Its currently one of the hottest topics in physics. The module provides teachers with tools to show how dark matter was discovered, to explain why it remains a mystery, and to share the passion of scientists who are trying to discover what its made of.

• http://www.perimeterinstitute.ca

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In astronomy and cosmology, dark matter is a form of matter that is undetectable by its emitted electromagnetic radiation, but whose presence can be inferred from gravitational effects on visible matter and background radiation. According to present observations of structures larger than galaxies, as well as Big Bang cosmology, dark matter accounts for the vast majority of the mass in the observable universe.

Dark matter was postulated by Fritz Zwicky in 1934, to account for evidence of "missing mass" in the orbital velocities of galaxies in clusters. Subsequent to then, other observations have indicated the presence of dark matter in the universe, including the rotational speeds of galaxies, gravitational lensing of background objects by galaxy clusters such as the Bullet Cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies.

Dark matter plays a central role in state-of-the-art modeling of structure formation and galaxy evolution, and has measurable effects on the anisotropies observed in the cosmic microwave background. All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation: the remainder is frequently called the "dark matter component," even though there is a small amount of baryonic dark matter. The largest part of dark matter, which does not interact with electromagnetic radiation, is not only "dark" but also, by definition, utterly transparent.

The vast majority of the dark matter in the universe is believed to be nonbaryonic, which means that it contains no atoms and that it does not interact with ordinary matter via electromagnetic forces. The nonbaryonic dark matter includes neutrinos, and possibly hypothetical entities such as axions, or supersymmetric particles. Unlike baryonic dark matter, nonbaryonic dark matter does not contribute to the formation of the elements in the early universe ("big bang nucleosynthesis") and so its presence is revealed only via its gravitational attraction. In addition, if the particles of which it is composed are supersymmetric, they can undergo annihilation interactions with themselves resulting in observable by-products such as photons and neutrinos ("indirect detection").

Nonbaryonic dark matter is classified in terms of the mass of the particle(s) that is assumed to make it up, and/or the typical velocity dispersion of those particles (since more massive particles move more slowly). There are three prominent hypotheses on nonbaryonic dark matter, called Hot Dark Matter (HDM), Warm Dark Matter (WDM), and Cold Dark Matter (CDM); some combination of these is also possible. The most widely discussed models for nonbaryonic dark matter are based on the Cold Dark Matter hypothesis, and the corresponding particle is most commonly assumed to be a neutralino. Hot dark matter might consist of (massive) neutrinos. Cold dark matter would lead to a "bottom-up" formation of structure in the universe while hot dark matter would result in a "top-down" formation scenario.

As important as dark matter is believed to be in the universe, direct evidence of its existence and a concrete understanding of its nature have remained elusive. Though the theory of dark matter remains the most widely accepted theory to explain the anomalies in observed galactic rotation, some alternative theories such as modified Newtonian dynamics and tensor-vector-scalar gravity have been proposed. None of these alternatives, however, has garnered equally widespread support in the scientific community.

• http://en.wikipedia.org/wiki/Dark_matter
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Category:

Science & Technology

Tags:

• dark
• matter
• engery
• astronomy
• cosmology
• electromagnetic
• radiation
• gravity
• gravitational
• background
• galaxies
• clusters
• big
• bang
• mass
• lensing
• cosmic
• microwave
• atoms
• neutrinos
• axions
• supersymmetric
• non
• baryonic
• particles
• universe
• photons
• hot
• cold
• theories

[shifr3snak3]

If aliens see this video they will never land on earth.

[Debbie321lopez]

The person who narrates this makes this interesting subject.. just.. plain stupid...

[1958kz]

How nice of them to avoid the question they asked. Yeah they touched on it but they did not go into why the stars were too fast.

[kerbain]

So the dude goes to weigh a juice carton, when it starts turning into random stuff right in front of his face. He just laughs and walks away... Only for it then to turn into a fecking SUN!! aaaannd everyone's dead...

Good info, but that was my favourite bit. 

[elmotouchesme97]

@Debbie321lopez i understand you. they dumb it down so that retards can understand it, but if you're retarded, don't watch a video about such a complex and interesting subject.

[AsianKatana]

THIS NARRATOR IS ANNOYING AND UGLY AS FUCK!

[sunriseger]

wtf... this nerdy narrator fucks all the nice "black holes" and "dark energy"

[Difius]

The subject is farly interesting, the narrater sounds sooo dull.

[ibman7]

3:16 is that Ray and 1:01 SEXY BABE

[crysisnov]

@XxDeapAbyss Dude, I think you are taking this a bit too serious.. It seems as if you are very excitable or sensitive about this. I would not care about any generalization of any kind of people, when it is merely meant as a joke. You could make fun about Norweigans, I wouldn't find it offensive.

[XxDeapAbyss]

@crysisnov I don't care if you got that from graffiti on the back of a bus! I certainly don't think it was a joke and that's not the fact that I didn't get it, because I did get it. That "generalization" on Canadians is like the generalizations of black guys, gingers, American's, and even Norwegians such as yourself. It's prejudice. How would you like it if the only thing you saw on the internet was : Norwegians are all a bunch of viking idiots that live in igloos?

[R4Zy3L]

Couldn't they find a human to narrate this video?