Which is evidence for the existence of dark energy?(1 point)
Responses
Pulsars that seem to be moving closer at an accelerating rate.
Pulsars that seem to be moving closer at an accelerating rate.
Supernovae that are moving away at an accelerating rate.
Supernovae that are moving away at an accelerating rate.
Galaxies that are rotating at a constant rate.
Galaxies that are rotating at a constant rate.
Black holes that are expanding at a constant rate.
Black holes that are expanding at a constant rate.
Supernovae that are moving away at an accelerating rate.
The evidence for the existence of dark energy is primarily based on the observations of supernovae that are moving away at an accelerating rate. This observation suggests that there is a force, known as dark energy, driving the expansion of the universe. Additionally, pulsars that seem to be moving closer at an accelerating rate also provide evidence for the existence of dark energy. Galaxies that are rotating at a constant rate and black holes that are expanding at a constant rate are not specifically related to the evidence for dark energy.
The evidence for the existence of dark energy comes from the observation that supernovae (exploding stars) are moving away at an accelerating rate. This observation suggests that there is a force pushing the galaxies apart and causing the universe to expand at an increasing rate. This force is known as dark energy.
To arrive at this conclusion, scientists use a method called Type Ia supernovae observations. They measure the brightness and redshift (the change in light wavelength) of these supernovae to determine their distance and velocity. By comparing the observed velocities of these supernovae with the expected velocities based on the understanding of gravity and the expansion of the universe, scientists found that the supernovae are moving away faster than expected.
This observation is consistent with the existence of dark energy, a mysterious form of energy that counteracts gravity and causes the accelerating expansion of the universe. Dark energy is thought to make up around 68% of the total energy content of the universe, and its nature is still a subject of active research in the field of cosmology.
Therefore, the correct answer is "Supernovae that are moving away at an accelerating rate" is the evidence for the existence of dark energy.
How did dark matter affect the development of structures in the early universe?(1 point)
Responses
It seeded the development of galaxies.
It seeded the development of galaxies.
It cooled pockets of gas to form nebulae.
It cooled pockets of gas to form nebulae.
It seeded the development of quasars.
It seeded the development of quasars.
It became part of black holes.
It seeded the development of galaxies.
How has scientific understanding about the composition of the universe changed over time? Select the two correct answers.(1 point)
Responses
The percentage of ordinary matter has grown in scientists' estimates since the 1970s.
The percentage of ordinary matter has grown in scientists' estimates since the 1970s.
The percentage of unknown material has grown in scientists' estimates since the 1970s.
The percentage of unknown material has grown in scientists' estimates since the 1970s.
The percentage of dark matter has shrunk in scientists' estimates since the 1980s.
The percentage of dark matter has shrunk in scientists' estimates since the 1980s.
The percentage of dark energy has shrunk in scientists' estimates since the 1980s.
The percentage of dark energy has shrunk in scientists' estimates since the 1980s.