Question

1. A person standing on Earth drops a ball. At the same time, a person standing at the bottom of a spaceship accelerating at 9.8m/s^2. In the absence of any significant field in deep space, drops a ball. What would these people observe

2. Research general relativity and problems with the theory. Identify two possible solutions to problems with general relativity and the behaviour of galaxies. Do the solutions seem plausible to you? Why or why not?

Answer 1

1. According to the theory of general relativity, gravity and accelerations are the same. We can't distinguish the system is in the gravitational field or is accelerating! Any experiment done in gravity is the same as done in an accelerating system.

So, the people will observe the ball falling towards the ground with a constant acceleration of 9.8 m/s2 and hitting the floor at the same time if fallen from the same height.

2. Here I discuss a few problems in general relativity.

a) Expanding universe. - General theory predicts the expansion of the universe is because of repulsive force call 'DARK ENERGY', but it fails to explain what is the origin of Dark energy.

Possible solution - Dark matter - the matter, we can not detect experimentally but exists in calculations of indirect observations(observations of different other species in the space.). This can be due to the attraction from a very large distance, so the universe is getting expanded.

b) Origin of the universe - We are unable to tell which theory of the development of the universe [ big bang theory] is right using general relativity. ( eg. big band theory, oscillatory theory, steady-state theory,etc.)

Possible solution - Big bang theory can be the possible solution as it's is the most popular theory. Still, it doesn't answer all the question, It may tell us how the universe is formed?