Teacher problems

[TheGoldenGriffin]

Your equation seems right. But there but all the evidence suggests that there is an x. I'll explain how the scientists concluded that dark matter exists. You know what a galaxy is right? It is a body of billions of stars, remnants if stars, and dust and gas, and at the center of most is a supermassive black hole or SMBH. Also, objects that orbit close to the center moves faster an object near the edge. Just like how Mercury travels around the sun and Neptune travels slower than Mercury around the sun because Neptune orbits billions of miles farther away from the sun than Mercury. Stars that orbit near the center of the galaxy should move faster than than stars orbiting at the edge of the galaxy right? Well, scientist have charted the orbital speeds of different stars and all the stars move at more or less the same rate. That means that the stars near the center of the galaxy move almost at the same rate as the stars near the edge of the galaxy. But there is no more to the galaxy after the edge, so the stars on the edge are moving way to fast right? Unless, that isn't the real edge of the galaxy. There is still more stuff orbiting the galaxy from much farther away. And since all the stars are orbiting the center of the galaxy at about the same rate, that means all the stars are actually orbiting at the center of the galaxy compared to the whole galaxy. But we can't detect anything after the apparent edge of the galaxy so there can't be anything there right? Okay fine, lets assume that the whole galaxy is where the stars are. The scientists can calculate the mass of the whole galaxy with different methods. They can use the orbital speed chart to calculate how much stuff is orbiting the galaxy because they know how the speed changes from the center to the edge. The more mass the galaxy has, the more stars and stuff there are, the brighter the galaxy is. The scientist can also use the brightness it determine the mass. Stars shine and the brighter the galaxy is, the more stars there are, and the more massive a galaxy is. Here's the problem. The mass determined by the brightness method is only 20%-10% of the mass determined by the orbital method. The brighness method only uses the matter that emits or reflects light, like the stars. That means 80%-90% of the mass that makes up the galaxy is not interacting with light at all, so the apprent edge of the galaxy isn't really the real edge of the whole galaxy and that there is more to the galaxy than the stars and remnant of stars and dust and gas and the stars really are all orbiting near the center. And because it doesn't interact with any kind of electromagnetic radiation it makes it hard to study. But not impossible. The discovered stuff is called dark matter. Pretty much all off the stuff we know about dark matter so far is because of light ironically. Gravitational lensing is evidence that dark matter exists. If there is a lot if dark matter in an area in space, the gravity from it can bend light like a lens. It's like looking through a fish bowl. You can see through it, but the light going through it is bending the path of light, distorting the background. Even though the glass and water is clear, you can tell its there because it is changing the path of light coming from the backround and distorting it. The masses of dark matter in space distorts the light coming from distant galaxies and using this, the scientists actually made a map of where dark matter is in space. But it still doesn't explain a lot which is why dark matter is still poorly understood. But dark matter is most likely made of WIMPs but it still isn't proven.