Question

What is the one property of dark matter we can measure? a) Color. b) Mass. c) Weight. d) Temperature. e) Chemical composition

How are the tiny temperature and density fluctuations in the cosmic microwave background (CMB) related to galaxies and clusters of galaxies we see in the present-day universe? a) There is no relationship. b) Warmer and denser regions in the CMB contain the least amount of dark matter. c) Warmer and denser regions in the CMB hide galaxies and galaxy clusters from our view. d) Warmer and denser regions in the CMB do not have enough hydrogen and helium to make present-day galaxies and galaxy clusters. e) Warmer and denser regions in the CMB are locations where galaxies and galaxy clusters are most likely to form

Answer 1

1. Mass of dark matter can be measured.using galaxies which distort light mapping of dark matter is done.

Based on the motion of spiraling galaxies scientists expected that centre should move faster than edges but thay found that stars at both places were moving with same speed. Moreover when they calculated mass of cluster of galaxy they found that if cluster really had this mass it would fly apart. for stability it must contain more mass tham measured and they named this mass as dark matter. Since we can't use existing astronomical instruments to measure it so using gravitational lenses (light bends near heavier celestial bodies) mapping of dark matter is done.

2. Warmer and denser regions in the CMB are locations where galaxies and galaxy clusters are most likely to form.

in earlier universe those places indicating hot and denser region are the location where most of galaxies and cluster exists today. they gives the information of formation of galaxies and clusters which exists today.