The Dark Matter Mystery: 39 Billion Missing Suns

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The Mystery of Dark Matter (Chapter 2/4): 39 Billion Missing Suns.

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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The Dark Side of the Cosmos

Much of the picture of cosmic evolution, called standard cosmology, is well grounded in fundamental physics, but makes up only part of the story. Standard cosmology involves detailed models, whose predictions agree with, and explain, much of what astronomers see. However, there are a growing number of observations that are deeply puzzling.

For example, a number of independent astronomical observations have provided strong evidence for the existence of vast quantities of matter that do not emit or reflect electromagnetic radiation of any type (visible light, microwaves, gamma rays, etc), and thus cannot be seen. It is called dark matter. How do we know it's there? Even though we cannot see it, it exerts very clear gravitational influences on the matter and radiation we can see.

For example, Albert Einstein's theory of space, time, and gravity, called general relativity, tells us that any gravitating mass (the Sun, a galaxy, a cluster of galaxies, etc.) warps the spacetime around it in such as way that a light ray passing nearby is deflected. Gravity bends light. Astronomers find that the amount of bending around, say, a typical cluster of galaxies, is far greater than can be accounted for by the visible mass in the cluster. There appears to be a great deal of invisible mass. Current data suggests that there is more than five times as much dark matter as ordinary matter (atoms) in the universe. What is dark matter made of, and can it be detected in laboratories here on Earth? An intense, worldwide effort is currently underway to try to answer these questions.

Another profound puzzle stems from astronomical observations indicating that the cosmic expansion of space is happening at an accelerating pace. But in a universe with only matter (dark or otherwise), gravitational attraction would slow down the expansion, just like a ball, thrown upwards, slows down due to Earth's gravitational pull. The acceleration can be explained by the assumption that the universe is filled with an unusual form of energy called dark energy that makes up 70% of the universe's total energy. But what, exactly, is this dark energy, and how does it fit in with the rest of physics? To date, no one knows the answer.

• http://www.perimeterinstitute.ca/en/Outreach/What_We_Research/Cosmology/

This presentation is available to educators on DVD and comes complete with specially-crafted teacher notes.
• http://www.perimeterinstitute.ca

The Mystery of Dark Matter Video Game
• http://perimeterinstitute.ca/dark_matter_game/index.html
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Category:

Education

Tags:

• dark
• matter
• energy
• suns
• stars
• galaxies
• mass
• speed
• universe
• science
• cosmos
• standard
• cosmology
• physics
• astronomers
• electromagnetic
• radiation
• visible
• light
• microwaves
• gamma
• rays
• gravitational
• einstein
• space
• time
• gravity
• general
• relativity
• clusters
• atoms
• expansion
• acceleration

[bbphnix]

I hate the way this guy talks.... I don't know why, but there's just something about the way he pronounces everything.... it's getting on my nerves...

[Collision5152]

a vaaaast collection of staaaaars

[ThePengwyn]

@bbphnix he sounds very condescending

[thegeffc]

brilliant video

[khijasmith]

Very enjoyable thank you

[alexasmithy]

great video thanks

[TheOneRebornElyrize]

@sindarapos well as i said, im not nearly as interested as you so im not rly memorizing stuff >.> i just like looking at theories and stuff so..yea.. sorry for not being much help ^^'

[sindarapos]

@TheOneRebornElyrize Hehe, oh well. Back to wikipedia, or other youtube video's it is :P.

Do you have any other sources you might want to point out?

[TheOneRebornElyrize]

@sindarapos ah well.. thought the same of you when you wrote that way xD though i think youre far more interested in this than i xD

[sindarapos]

@TheOneRebornElyrize Such a shame that you think of me that way. I'd love you to explain the details of this. I'm very interested in physics. I was just replying in such a crude manner because you were not helping me at all.

To me it sounded like: " ... you're wrong, you do know that? Because if you don't, than ur even a bigger fool".

[TheOneRebornElyrize]

@sindarapos well i dont think youre gonna listen even if i explain it throughly.. so..yea..bye :P

[sindarapos]

@TheOneRebornElyrize No, I didn't know that. However, I'd rather go with xxxaudiophilexxx's more acurate explanation, who provides the argumentation for my doubts about the orbital method.