B4 plase all mcq ans If an astronaut travels inside the event horizon of a black hole, what phenomenon will he observe?O A. He will see the light emitted by stars outside of the eventhorizon.O B. Light from the world outside the event horizon becomesinvisible.OC. The astronaut will encounter a spherical wall of matter.O D. The astronaut will see that all light is redshifted.The astronaut will observe the stoppage of time.58A particle called the pi meson has a lifetime of 18 ns (ns = 10° s) when it is at rest. In a particle accelerator, pi mesons are produced thatare moving close to the speed of light. What is the lifetime of the rapidly moving pi mesons?O a The pi mesons have a lifetime much longer than 18 ns if theyare moving fast.cross outut ofO b. The pi mesons have a lifetime much smaller than 18 ns if theyare moving fast.cross outOc. The pi mesons have a lifetime that is 18 ns if they are movingCIOSS outfastOd. The pi meson becomes a stable particle and doesn't decay if itis moving fast.cross out53Which is the most difficult type of X-ray binary companion star to observe?Select one:but ofLow-mass companion stars, because they are so dim relativeO a.to the accretion disc.O b. Low-mass companion stars, because they are rapidlydestroyed by a black hole.O c. High-mass companion stars, because they lose their materialat an extremely high rate to the black hole disc, making itbrighter than them.O d. High-mass companion stars, because they expand and coolrapidly when near a black hole.

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If an astronaut travels inside the event horizon of a black hole, what phenomenon will he observe? O A. He will see the light emitted by stars outside of the event horizon. O B. Light from the world outside the event horizon becomes invisible. OC. The astronaut will encounter a spherical wall of matter. O D. The astronaut will see that all light is redshifted. O E. The astronaut will observe the stoppage of time.

If an astronaut travels inside the event horizon of a black hole, what phenomenon will he observe? O A. He will see the light emitted by stars outside of the event horizon. O B. Light from the world outside the event horizon becomes invisible. OC. The astronaut will encounter a spherical wall of matter. O D. The astronaut will see that all light is redshifted. O E. The astronaut will observe the stoppage of time.