Cosmology 101: Dark matter

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In this series I give you an overview of important ideas in the area of cosmology. This video is the second in the series, and focuses on dark matter.

Using various detectors and research methods, astronomers have determined that the stuff we see in space — stars, gas, and dust — amounts to less than 5 percent of the universe. This stuff is ordinary matter, and it's made up of protons, neutrons, and electrons. Scientists call ordinary matter "baryonic matter" because protons and neutrons are subatomic particles called baryons.

So if ordinary matter is only about 5 percent of the universe, what's the other 95 percent? Well, about 23 percent is something called dark matter. The remaining 72 percent is a mysterious pervasive force called dark energy. I'll explain more about dark energy in my next video.

Alright, back to dark matter. This mysterious mass is a type of matter that doesn't emit, absorb, or reflect any type of light (so, for example, it doesn't emit X rays or absorb infrared radiation). Dark matter is therefore invisible. If it's invisible, how do astronomers have any idea it's there? Dark matter interacts with ordinary matter through gravity. Its gravitational interaction is how astronomers first found out dark matter exists.

In 1933, a Swiss astrophysicist by the name of Fritz Zwicky first proposed dark matter's existence. While studying the Coma galaxy cluster, he found that the galaxies' gravity alone was much too small to hold the cluster together.

The next round of evidence came about 40 years later, in the 1970s. Astronomers charted the velocity of stars at various distances from the center of a galaxy, and plotted the velocity versus the distance. This plot is called a rotation curve. They expected the velocities to reach a maximum and then decrease farther from the center — but the data showed otherwise. The velocities reach a maximum and then plateau. With velocities of this magnitude at the outer edge of galaxies, the stars should be flung out of their orbits. But they aren't. So some sort of mass that we can't detect must hold these outer stars in orbit.

Massive galaxy clusters also show evidence of dark matter. A very massive object — such as a galaxy cluster — can bend and magnify light from galaxies behind it. That massive object acts as a gravitational lens. In this image of galaxy cluster Abell 2218, you'll see numerous blue arcs. Those are background galaxies distorted and magnified by the cluster's gravity. Astronomers study the sizes and shapes of those arcs to determine the cluster's mass. By comparing that calculated mass to the mass that comes from only luminous objects (the galaxies), they can determine how much dark matter is in the cluster.

Today, astronomers are pretty confident that dark matter does in fact exist. They've created numerous "dark matter maps" using different techniques, including gravitational lensing of galaxy clusters. The next step is finding out what it is. As I said earlier, dark matter doesn't emit, absorb, or reflect any type of light. So, it's likely some sort of mysterious non-baryonic particle, meaning it's not made up of the same stuff as ordinary matter (protons and neutrons).

Astronomers split non-baryonic dark matter into two categories: hot and cold. These titles don't mean that if you touch them, you'll feel something that's hot or cold. Hot means that early in the universe, these particles traveled very, very fast — almost at the speed of light. Cold means that early in the universe the particles traveled slower.

How does particle speed relate to figuring out what dark matter is? Well, slower particles will bunch up into small structures earlier in the universe. Those small structures will eventually collide and merge, forming larger structures. Astronomers believe this is how structure forms and evolves in our universe — smaller structures eventually merge into the massive superclusters and filaments we observe today. Astronomers simulate structure evolution with cold dark matter, and create models that resemble today's universe. This simulation shows dark matter distribution. Brighter areas represent more dense regions.

OK, so what is cold dark matter? That's a good question. Scientists aren't sure yet, but they believe it's a massive, charge-neutral as-of-now hypothetical particle called the neutralino. They haven't found this particle yet, but the Large Hadron Collider particle accelerator may change that after it restarts in the fall of 2009.

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[sandustanBrasov]

• SandustanBrasov

The UNIFIED LAW is the LAW of the UNIVERSAL ATTRACTION FORCES= of the GRAVITATIONAL INTERACTION FORCES = of the ELECTROMAGNETIC FIELD FORCES produced by the inner movement of the inertial rotation of the ethereal matter from bodies and substances. This, because, the ethereal particles are in continuous movement through the them nature, being electrical – produce electrical energy, being named and electrogenic particles.

[sandustanBrasov]

• SandustanBrasov

The physicists show that about the discovery the Higgs boson it desire and the discovery the origins of the bodies'mass; the discovery the dark matter, the discovery the superior dimensions and the demonstration of the superposition. But as a result to the collisions of particles- the black holes had appeared not, the Big-Bang had appeared not demonstrating that the Large Hadron Collider bring not about us the Apocalipse.

[sandustanBrasov]

• SandustanBrasov

Between 1930...1935 the discord was photon of light.The opinion of physicists had not adopted existence in flight to photon, and photon remain without mass. If photon has not mass, he cannot interact with nothing on trajectory and the light speed remain constant lengthways the trajectory. Thus, in place let to consider that the photons lose themselves the speed on way as result the them interaction with the intergalactic matter, they had set the Universe let it dilate entirely

[sandustanBrasov]

SandustanBrasov

Today, on measure that the theory advances from classic mechanics to the quantum mechanics the particle and the wave are gradual dematerialize. The modern physics is blocked by enunciation of some laws and mistaken principles as: relativity theory, Hubble's law, postulation that the atom can't emit and absorb radiations continously, admitting the postulate what claims the photons without mass a.s.o.These guide- us at supernatural and at the technical and technological blocage

[sandustanBrasov]

SandustanBrasov

As a result of the wrong interpretation of the Michelsom-Morley(1881)'s experiments which had demonstrated that the ETHER is entirely trained with the mass and the Earth's atmosphere, in 1905 A.Einstein renounced at the ether notion, at absolute space and set the relativist mecanics' base. He emits the two restricted relativity principles through which excludes the Ether, impose as limit of bodies' movement -the light speed and denatured completely the classic dynamics reality

[sandustanBrasov]

• SandustanBrasov

A.Einstein through the his relativity to REVERSED the reality of the our terresterial world. He remove the ETHER from physics and give materiality the space and the time. But the SPACE limit the place where it can unfolding material actions and the TIME mark the period of unfolding to some material actions. The space and the time are only ABSTRACT notions, absolute and colateral which show where and when it unfolding certain material actions.

[maxpainrg2]

In my theory

[maxpainrg2]

In my theory

[maxpainrg2]

Trying to observe dark matter is (I'm my theory) impossible as it would be like looking for time.

[adelle0001]

gandang topic astronology!