Dark Matter :: physics science space

Dark MatterFor centuries, physicists and philosophers alike fork out wondered what makes up our universe. Aristotle thought that all publication came in one of quaternary 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 globe 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 settle down dont know what form of matter makes up 95% of the universe. Physicists have named this private substance dark matter, for it can not be detected by observation (it does not emit visible or other frequence light waves). However, we know that dark matter must(prenominal) exist, following Newtons world(a) law of gravity.There are two ways to prove the existence of dark matter. We know that the universe must have a sure throne in order for its attractive gravitational forces to slow the intricacy of the universe which started at the big bang. We can precisely calculate the set up at which the universe is expanding currently, and how fast it has expanded in the past. From this we get the supposed flowerpot 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 test about 5% of our universe.We can likewise prove that dark matter exists in galaxies by examining how they spin. When an purpose rotates in a circular orbit, the object has a tendency to fly off in a room tangent to the orbit. If the stays within the orbit, it has a radial acceleration which is live to its velocity squared over the radius of the orbit. The only force which is property the body in the orbit is the force of gravity, which is dependent on the mass of the syst em. 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 alfresco the galaxy. In the case of the galaxy shown in the photo, dark matter must be present in the dark space between the meat of older yellow stars and the outer ring of young, blue stars.