12. Which is evidence for the existence of dark energy?
*
1 point
galaxies that are rotating at a constant rate
Pulsars that seem to be moving closer at an accelerating rate
Black holes that are expanding at a constant rate
Supernovae that are moving away at an accelerating rate
Supernovae that are moving away at an accelerating rate is evidence for the existence of dark energy.
The evidence for the existence of dark energy is supernovae that are moving away at an accelerating rate.
The evidence for the existence of dark energy can be found in the observation of supernovae that are moving away at an accelerating rate. To understand how this provides evidence for dark energy, we need to have a basic understanding of the expanding universe.
In the early 20th century, Edwin Hubble discovered that galaxies are moving away from each other, which suggests that the universe is expanding. The rate at which the universe expands is known as the Hubble constant.
Scientists expected that the expansion of the universe would gradually slow down over time due to the gravitational pull between galaxies. However, in the late 1990s, observations of distant supernovae revealed a surprising result. These supernovae appeared fainter than expected, suggesting that they were moving away at an accelerating rate.
This observation challenged the conventional understanding of the universe's expansion and led to the proposal of dark energy. Dark energy is a hypothetical form of energy that is believed to permeate space and drive the accelerated expansion of the universe.
Therefore, the observation of supernovae moving away at an accelerating rate is considered evidence for the existence of dark energy.