Quiz · Dark Matter and Galaxy Rotation Curves

Question 1What is the central topic of the lecture?

The mystery of dark matter revealed by galaxy rotation The laws of Newtonian mechanics in outer space The collision of galaxies in the Bullet Cluster The brightness of stars near galaxy centres

Question 2What happened to the search for the leading dark matter candidates?

They were detected within a decade as expected They were quickly ruled out by lensing studies Decades of experiments found no definitive signal They were confirmed by colliding galaxy clusters

Question 3What provided the most compelling independent evidence for dark matter?

The luminosity of distant galaxies Gravitational lensing of distant galaxies Dust clouds hiding ordinary matter The flat shape of rotation curves

Question 4What exactly do galaxy rotation curves measure in a galaxy?

How quickly stars orbit at different distances from the centre How brightly the stars shine at the edge of galaxies How often two galaxies collide with one another How much dust surrounds the youngest hot stars

Question 5What did Newtonian mechanics predict about stars in the outer regions?

They should orbit more slowly than those nearer the centre They should orbit faster than all the other stars They should escape from their galaxies completely They should shine more brightly than inner stars

Question 6What do the observed flat rotation curves imply about visible matter?

It is concentrated at the edge of each galaxy It accounts for only a small fraction of the total mass It moves faster than the surrounding dark matter It gradually disappears near the galactic centre

Question 7How is dark matter detected, according to the speaker?

Through the light that it slowly absorbs Purely through its gravitational effects By measuring the heat from dust clouds By tracking its faint radio emissions

Question 8Which widespread misconception about dark matter does the speaker reject?

That it plays no role in galaxy rotation That it was discovered within a single decade That it is ordinary matter hidden in dust clouds or dim stars That it can never be studied inside laboratories

Question 9What problem do theories that modify the laws of gravity still face?

They predict flat rotation curves too accurately They were rejected before any experiments began They require telescopes faster than any that exist They struggle to account for observations of colliding galaxy clusters

Question 10What does the example of the Bullet Cluster demonstrate?

That most of the gravity comes from hot gas clouds That dark matter emits light during cluster collisions That rotation curves change shape after collisions That the mass revealed by lensing is separated from the visible gas