Which of the two best summarize what we mean by dark matter? In my opinion, the best summary is given by sci-fi writer Arthur C Clarke. He wrote a science fiction novel called “Rendezvous With Rama” in which an alien race called theuders sent explorers who were looking for a mythical land that existed in their legends. As the explorers departed, they encountered a rotating disk, which was much like a planetarium at the galaxy’s core.
The disk was hollow, and it was filled with dark matter. The interior was filled with gas that rotated, which gave off radiation that the explorers could not see. These gases also contain hydrogen and helium, which collectively make up planets. Of all the planets found to exist around other stars in our galaxy, our own solar system seems to have the most dark matter in our “nebular” (astronomers speak of these as “galactic” since they are beyond the Galaxy’s edge) cloud.
So, the question which of the two answers is correct is which of the following best sums up what we mean by dark matter? The answer to the first question is that our solar system is completely made up of it. The second question is that our galaxy is not completely made up of it. And this leads to the third answer, which is that both our galaxy and our solar system are made up of it.
Now let us answer the first question first. In order to get the answer “yes”, we must first understand what makes up our solar system. All of the elements which compose the planets are in perfect balance, meaning they are either too heavy or too light. We actually have an amount of dark matter, which consists of more free space, which is called “critical mass” in particle physics. This is the bulk which makes up the atomic nuclei of every atom.
Now let us answer the second question. In order for stars to form, all of the elements which compose the solar system must be in their right places. Otherwise, the stars which are very similar in composition will be pulled apart, like a matchbox. There will be a lot of stars which are very similar to our own, but they will go on flying away due to their own gravity and separate from each other. The most interesting aspect of this is that nearly all of the galaxies that we observe have a critical mass, which is much greater than the atomic nuclei, to make up their cores.
The third answer is what can give rise to dark matter in our own galaxy. Since everything which makes up the entire universe is moving at the speed of light, it follows that the very largest things, including large ice-sized grains like dust, will eventually become accretion disks, which will be very similar to our own gas sphere. These will then gradually expand, until they reach the velocity of the solar system which is close to the solar wind, and very close to the potential of the forming black holes. Thus, if you want to find out which of the following best summarizes what we mean by dark matter, you must also remember that the most massive disks of gas which are extremely hot, very compact, and move rapidly, will also be very closely observed by astronomers right now.
The fourth answer is which of the following best summarizes what we mean by dark matter? If you put two identical disks together, one rotating slowly, and the other rotating very quickly, and the space between them, you will get the effect of a spiral. This means that the space which separates the two
will have a definite shape which has a negative y-axis direction when viewing it from above, and an essentially zero y-axis direction viewing it from below. In a similar way, if we place identical discs on uniformly shaped spindles which rotate at different velocities, and which have similar gravity, you will get the effect of a doughnut.
The fifth answer is which of the following best summarizes what we mean by dark matter? If you put a ball of string inside a vacuum chamber and put in radiation coming from very hot particles which come from stars or other kinds of very high energy sources, you will find that the string will slowly expand, until it reaches the ends of the chamber. This is because a large fraction of the string particles will be trapped inside the chamber, while the rest will fall to the floor. These particles will be spread out into different directions, which will give rise to a random variety of swirl patterns which astronomers study with great interest.