Dark Matter For centuries, physicists and philosophers alike have wondered what makes up our universe. Aristotle thought that all matter came in one of four forms: Earth, Air, Fire, and Water. Since then we have come a long way, with the discovery of the atoms and the subatomic particles they are made of. We can even guess at what makes up protons and neutrons. We have since then discovered and predicted the existence of particles other than the atom, such as the photon, neutrino, axion, and many others. Despite all our advances in particle physics and astrophysics, we still don't know what form of matter makes up 95% of the universe. Physicists have named this mysterious substance dark matter, for it can not be detected by observation (it does not emit visible or other frequency light waves). However, we know that dark matter must exist, following Newton's universal law of gravity. There are two ways to prove the existence of dark matter. We know that the universe must have a certain mass in order for its attractive gravitational forces to slow the expansion of the universe which started at the big bang. We can precisely calculate the rate at which the universe is expanding currently, and how fast it has expanded in the past. From this we get the theoretical mass of the universe. This figure falls far short of the visible mass of the universe, which consists of stars, planets, and hot gas. This is how scientists are able to prove that we can only see about 5% of our universe. We can also prove that dark matter exists in galaxies by examining how they spin. When an object rotates in a circular orbit, the object has a tendency to fly off in a path tangent to the orbit. If the stays within the orbit, it has a radial acceleration which is equal to its velocity squared over the radius of the orbit. The only force which is keeping the body in the orbit is the force of gravity, which is dependent on the mass of the system. Knowing this, physicists can calculate the mass of a galaxy by looking at how fast stars orbiting its center are moving. Physicists can also calculate where the highest percentage of dark matter should be in the galaxy. In most cases, it is located in a ring just outside the galaxy. In the case of the galaxy shown in the photo, dark matter must be present in the dark space between the nucleus of older yellow stars and the outer ring of young, blue stars.
In the first chapter we meet some of the characters and what they do. Both Daniela and Jason Dessen gave up their careers to start a family together. Jason goes to a party held for his former colleague, Ryan Holder, celebrating a Prize that he had earned. He and Jason talk and Jason gets enraged and leaves the party early. On his way home a kidnapper approaches him and forces him into a SUV. He takes Jason to an abandoned warehouse and injects a needle into his neck and slowly Jason goes unconscious.
At a spiritual level, the Universe is made up of something even more basic. These basic particles are known as the three subtle basic components (trigunās) namely Sattva, Raja and Tama. In the word triguna, "tri" stands for three and "gunās" stand for subtle-components.
In 1803 this theory was finalised and stated that (1) all matter is made up of the smallest possible particles termed atoms, (2) atoms of a given element have unique characteristics and weight, and (3) three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules).
...f gas, which collapsed and broke up into individual stars. The stars are packed together most tightly in the center, or nucleus. Scientists believe it is possible that at the very center there was too much matter to form an ordinary star, or that the stars which did form were so close to each other that they coalesced to form a black hole. It is argued that really massive black holes, equivalent to a hundred million stars like the Sun, could exist at the center of some galaxies
Matter, as we conceive it today, did not exist after the Big Bang, because the temperature was too high for that. While trying to join protons and electrons, light continually crossed apart. Only when the universe had cooled to 3,000 K, the atoms are held together and the light was beginning to happen.
Dark Energy is a theoretical repulsive force that counteracts gravity and causes the universe to expand at an accelerating rate. More is unknown than known about Dark Energy. There had been many theories about Dark Energy before HST, but no one had hard evidence. The HST provided evidence
The American scientist John Wheeler coined the phrase “black hole” in 1969 to describe a massively compact star with such a strong gravitational field that light cannot escape. When a star’s central reserve of hydrogen is depleted, the star begins to die. Gravity causes the center to contract to higher and higher temperatures, while the outer regions swell up, and the star becomes a red giant. The star then evolves into a white dwarf, where most of its matter is compressed into a sphere roughly the size of Earth. Some stars continue to evolve, and their centers contract to even higher densities and temperatures until their nuclear reserves are exhausted and only their gravitational energy remain. The core then rushes inward while the mantle explodes outward, creating neutron stars in the form of rapidly rotating pulsars. Imploding stars overwhelmed by gravity form black holes, where the core hits infinite density and becomes a singularity (some estimate it at 10^94 times the density of water).
Black Holes are mostly found inside of the Milky Way. There are many types of galaxies and many different types of Black Holes. A normal galaxy has gases and stars
Every day we look into the night sky, wondering and dreaming what lies beyond our galaxy. Within our galaxy alone, there are millions upon millions of stars. This may be why it interests us to learn about all that we cannot see. Humans have known the existence of stars since they have had eyes, and see them as white glowing specks in the sky. The mystery lies beyond the white glowing specks we see but, in the things we cannot see in the night sky such as black holes.
Black Holes The term black hole was first used in 1969 by the American scientist
It is clear that we would need further evidence and advances in physics before it will be remotely possible to know the fate of our universe. Scientists now think, and mostly agree with each other that the fate of the universe depends on three main things: the overall shape or geometry of the universe, how much dark energy it contains, and on the “equation of state”; which determines how the density of dark energy responds to the expansion of the universe.
The Atomic Theory began in roughly 400BC with Democritus in Ancient Greece and is universally believed to be correct today. Democritus who was born in 460 BC and died 370 BC and is known as the father of modern science. Democritus proclaimed that everything is made up of atoms. He continued his theory to say that atoms will always be in motion, between atoms there is empty space, atoms are unbreakable, there are an infinite number of atoms all different sizes and shapes. He also said that iron atoms are solid and strong and have hooks to lock them together, water atoms are smooth and slippery, salt atoms have sharp jagged edges because of its taste and air atoms are light and spiralling.
A galaxy, also called a nebula, consists of billions of stars, interstellar gas, dust, and dark matter which are all bound to form a massive cloud in which we live in. Although it cannot be very well explained, dark matter makes up at least 90% of a galaxy’s mass. Galaxies also contain billions upon billions of stars and their diameter can range from 1,500 to 300,000 light years. That’s huge! The Milky Way, the galaxy in which we live in, is one of about 170 billion galaxies in the observable universe. Our Sun is one of the billions of stars in our galaxy, and our eight planets revolve around this star in only a tiny part of our galaxy. “The Earth’s solar system is believed to exist very close to the Galaxy’s galactic plane, due to the fact that the Milky Way essentially divides the night sky into two virtually equal hemispheres” ("All About the Milky"). It definitely makes people second guess the fact of there being life on other planets.
The Universe is a collection of millions of galaxies and extends beyond human imagination. After the big bang, the universe was found to be composed of radiation and subatomic particles. Information following big bang is arguable on how galaxies formed, that is whether small particles merged to form clusters and eventually galaxies or whether the universe systematized as immense clumps of matter that later fragmented into galaxies (Nasa World book, 2013). A galaxy is a massive area of empty space full of dust, gases (mainly 75% Hydrogen and 25%Helium), atoms, about 100-200 billion stars, interstellar clouds and planets, attracted to the center by gravitational force of attraction. Based on recent research, 170 billion galaxies have been estimated to exist, with only tens of thousands been discovered (Deutsch, 2011).
Two galaxies which are believed to revolve around our own are the Small and Large Magellanic Clouds. Only visible from the Southern Hemisphere, Magellan, the famous European explorer, was the first to describe these galaxies. Even though we know a great amount more than the astronomers in the past, there is still an even larger amount we do not know about the universe to this day. Even our own solar system contains many questions yet to be answered. Some of these include the possibility of a planet beyond Pluto (Planet X), the means by which the system was created, and even the possibility of a sister star to the Sun named Nemesis.