Dark Matter :: physics science space

Dark MatterFor centuries, physicists and philosophers uniform suck wondered what makes up our universe. Aristotle thought that all enumerate came in angiotensin-converting enzyme of four forms Earth, Air, Fire, and Water. Since then we have come a long way, with the uncovering of the atoms and the subatomic particles they are made of. We arouse even guess at what makes up protons and neutrons. We have since then discovered and predicted the existence of particles separate than the atom, such as the photon, neutrino, axion, and many others.Despite all our advances in particle physical science and astrophysics, we still dont know what form of matter makes up 95% of the universe. Physicists have named this mysterious substance grubby matter, for it can not be find by observation (it does not emit apparent or other frequency light waves). However, we know that dark matter must exist, pursual Newtons universal law of gravity.There are two ways to establish the existence of d ark matter. We know that the universe must have a certain mass in order for its attractive gravitational tears to slack up the expansion of the universe which started at the big bang. We can precisely send the rate at which the universe is expanding currently, and how fast it has expanded in the past. From this we pose 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 merely 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 beak 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 speedup 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 galax 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 and outside the galaxy. In the case of the galaxy shown in the photo, dark matter must be present in the dark space amongst the nucleus of older yellow stars and the outer ring of young, blue stars.