How has scientific understanding about the composition of the universe changed over time? Select the two correct answers.(1 point)
Responses
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 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 ordinary matter has grown in scientists' estimates.
The percentage of ordinary matter has grown in scientists' estimates.
The percentage of dark energy has shrunk in scientists' estimates.
The percentage of dark matter has shrunk in scientists' estimates since the 1980s.
The percentage of unknown material has grown in scientists' estimates since the 1970s.
The correct answers are:
1. The percentage of unknown material has grown in scientists' estimates since the 1970s.
2. The percentage of dark energy has shrunk in scientists' estimates.
Explanation:
1. The discovery of new particles and phenomena, such as neutrinos and dark matter, has led scientists to realize that a significant portion of the universe is composed of unknown material. This percentage has grown in scientists' estimates since the 1970s.
2. Dark energy, a hypothetical form of energy responsible for the accelerating expansion of the universe, was only discovered in the late 1990s. As scientists have refined their understanding of dark energy, the percentage attributed to it has shrunk in their estimates.
The correct answers are:
1. The percentage of unknown material has grown in scientists' estimates since the 1970s.
2. The percentage of ordinary matter has grown in scientists' estimates.
To determine these answers, we need to understand the changes in scientific understanding about the composition of the universe over time. Scientific knowledge about the composition of the universe is constantly evolving as new evidence and observations are made.
In the 1970s, scientists believed that the universe was primarily composed of ordinary matter, such as atoms and molecules. However, with advancements in astronomical observations and measurements, it became evident that there must be some form of unseen or unknown material influencing the dynamics of the universe.
This led to the concept of dark matter, a hypothetical form of matter that does not interact with light or other electromagnetic radiation but exerts gravitational effects on visible matter. Scientists started to realize that there must be a significant amount of dark matter in the universe to explain the observed motions of galaxies and the structure of the universe.
Therefore, the percentage of unknown material, specifically dark matter, has grown in scientists' estimates since the 1970s.
Additionally, the concept of dark energy emerged in the late 1990s. Dark energy is a hypothetical form of energy that is believed to be responsible for the observed accelerated expansion of the universe. As more research has been conducted on this topic, the percentage of dark energy in scientists' estimates may have changed.
However, the question asks for two correct answers. Therefore, the statement regarding dark energy is not confirmed in the given options. The only option remaining is that the percentage of ordinary matter has grown in scientists' estimates. This suggests that scientists have revised their understanding and now believe that ordinary matter makes up a larger proportion of the universe than previously thought.