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.
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.
The Large and Small Magellanic Clouds are among the highlights of the southern night sky. Only within the last century were astronomers able to verify their true nature. Although they seem to be two foggy patches possibly torn from the Milky Way, astronomers believe these are actually small galaxies gravitationally bound to the Milky Way like moons around a giant planet. The two Clouds of Magellan are like binary stars that gravity draws together to form a satellite galaxy.
Dark Matter is next largest ingredient, which only interacts with the rest of the universe through its gravity. Astronomers believe that the Universe is critically balanced between being open and closed. They derive this fact from the observatio...
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.
Dr. Bianconi and her team of research scientists utilized this data and rough estimates of the average size of a human cell to determine that there would likely be roughly 37.2 trillion cells in the average human body. Scientists mapped out the average surface area of a human and made calculations based on this finding. For Balakar, this means that there are certainly more cells in the human body than there could be galaxies. In determining the likely number of galaxies, astronomers have simply counted the number of galaxies in an individual section of the universe and multiplied that by the vast volume of space that exists in the known universe. By using this technique, scientists have estimated that there are 800 billion
The telescope made its one-millionth discovery in 2011. Before the Hubble Telescope scientist predicted the age of the universe to be around 10 to 20 billion years old. Hubble gave scientists the information to have a more precise answer of 13.7 billion years old. A main reason for this great discovery was Hubble’s observations of special types of bodies called Cepheid variable stars. Cepheid variable stars have very stable patterns of brightness that make them very effective at measuring distance. Although scientist know about the existence of dark energy now, because of the Hubble telescope they recovered the existence of dark energy in the early stages of the universe up to nine billion years ago. Dark energy is believed to accelerate the expansion of our universe, but it was first believed that after the Big Bang the expansion slowed
The idea that substances contain matter was not pulled out of thin air. Ancient Greek philosophers tried to prove the existence of matter which began with everything being made up of fire or water in different forms. Around 460 BC, a philosopher named Democritus described the tiniest piece of matter as being indivisible. This gave way to the name “atomos” or Greek for “no-cut”. Unfortunately, the most impactful philosopher, Aristotle, did not go along with what Democritus believed. To him, the four elements made up matter. These conflicting arguments surpris...
The concept of an “atom” first began in ancient Greece. According to Delgado, early philosophers “suggested that regular solids were fundamental parts of the universe, and Democritus’ teacher, Leucippus, had introduced him to the idea of an atomic system.” However, it wasn’t until the
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).
The theory of quantum mechanics has divided the atom into a number of fundamental sub-atomic particles. Although the physicist has shown that the atom is not a solid indivisible object, he has not been able to find a particle which does possess those qualities. Talk of particles, though, is misleading because the word suggests a material object. This is not the intention for the use of the word in quantum physics. Quantum particles are, instead, representations of the actions and reactions of forces at the sub-atomic level. In fact, physicists are less concerned with the search for a material particle underlying all physical objects and more interested in explaining how nature works. Quantum theory is the means that enables the physicist to express those explanations in a scientific way.
Energy is an odd concept, it is something that is neither here nor there yet has a profound impact on everything, both organic and inorganic. However, energy surrounds us in more ways than is commonly believed; it is possible that matter is only a form of energy. In fact, according to Albert Einstein, matter and energy are different forms of the same thing (“Do Antimatter and Matter Destroy Each Other?”). Through analyzing the superposition of bosons (particles without mass) and fermions (particles with mass), transformations between energy and matter, the creation of mass, and the mass of energy, the existence of what humans consider to be matter will be questioned.
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.
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. Another astronomical mystery is the creation of the universe. In time, many questions will be answered but some will always remain. Astronomy is something that will never be completely understood.
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).
The idea behind the Solar Nebular Hypothesis is that the solar system was condensed from an enormous cloud of hydrogen, helium, and a few other elements and rocks. Around five billion years this cloud of materials began to spin and contract together into a disk shape under their own gravitational forces. The particles started combined together, protoplanets, to eventually form planets. A great mass of the material eventually began to form together, protosun, and make up the sun.