Quantum fluctuations in the early universe a- were the seeds that grew into toda
ID: 2076694 • Letter: Q
Question
Quantum fluctuations in the early universe a- were the seeds that grew into today's galaxies. b. are the reason dark matter exists. c. were made of small black holes. d. had no effect on the current structure of the universe. e. can be observed with radio telescopes. Why can't dark matter halos collapse to be the same size as the visible parts of galaxies? a Dark matter can't dissipate its energy through radiation from collisions. b. Dark matter is made mostly of mini-black holes. c. Dark matter has much more angular momentum. d. Dark matter annihilates when it begins to get that dense. e. Dark matter particles are too large to collapse that much. Which of the following is true about neutrinos? a. They are an example of cold dark matter. b. They are an example of hot dark matter. c. They have been theoretically predicted, yet never detected. d. They must be much more massive than the dark matter candidate called photino. e. They account for all the dark matter in the universe. Dark matter is essential in understanding the formation of the large scale structure in the universe in that a. was clumpier than normal matter in the early universe. b. consists exclusively of antimatter particles. c. has a repulsive effect, just like the dark energy. d. explains the physics of black holes. e. cannot be made of elementary particles. The best hypothesis about the nature of dark matter is that it consists of particles with no electric charge would such particles have no electric charge? a. They cannot be more massive than an electron. b. If they did, they would emit photons as they move in external magnetic fields. c. Charged particles would have been all annihilated in particle-antiparticle collisions in the early universe. d. No elementary particle has electric charge. e. Charged particles formed only later inside stars. How do the properties of the CMB give support to the existence of dark matter? a. The CMB has the same temperature as the cold dark matter. b. The faint glow of the CMB was actually produced by dark matter particles as they annihilated normal matter particles. c. The opaque CMB is essentially hiding the dark matter that existed earlier in the universe. d. The CMB is too smooth to account for the structure we observe in the universe. e. The observed spatial scale of CMB clumsiness perfectly matches that of the dark matter. The future James Webb telescope is designed to observe the most distant galaxies in the universe. It will observe them in a. UV b. IR. c. visible. d. X-ray. e. radio.Explanation / Answer
7. (a)
Explanation:- Quantum fluctuations/variations act as seeds for structure formation. After the inflationary period of the early universe after big bang, when fluctuations are amplified, the density of matter will vary slightly from place to place in the Universe. Gravity will cause the more dense regions to start contracting, leading to the formation of galaxies. Hence the correct answer is (a).
8. (a)
Explanation:- Dark matter, a type of matter that does not seem to interact with the rest of the Galaxy's matter and energy in any way except through gravity. Since they cannot interact with anything, so they can’t collapse because that will require them to interact with the matter of galaxies. Hence the best explanation for this is (a).
9. (b)
Neutrinos (or more precisely sterile neutrino) are proposed as a candidate for the dark matter but they are very hot in the sense that their energies and velocity is much higher than as required for considered as a hot dark matter. So option (a) and (e) are ruled out. Also option (c) is not correct because they have been detected experimentally in 1956 itself. There is a lot of controversy on the mass of neutrino and photino and still no precise data is available but still photino is thought to be heavier. Therefore, the most correct option is (b).
10. (a)
Dark matter is needed to explain the observed properties of galaxy formation and clumping into groups and clusters. The dark matter should be cold to correctly reproduce the pattern of galaxy groups, filaments and clusters we observe in our Universe.
11. (b)
If dark matter is to consist of particles having electric charge then that particle would be able to interact with electromagnetic forces but the dark matter cannot interact with any forces except gravitational forces. So the correct answer is (b)
12. (e)
13. (b)