Which of the following possible outcomes regarding the universe do scientists think is most likely?
A.
The universe will continue to expand.
B.
The universe has completed its expansion.
C.
The universe will start shrinking soon.
D. The universe is already shrinking.
A. The universe will continue to expand.
To determine which of the given possible outcomes regarding the universe scientists think is most likely, we can refer to the current scientific consensus and observational evidence. The prevailing view among scientists is that Option A, "The universe will continue to expand," is the most likely outcome.
This conclusion is based on observations of the rate at which galaxies are moving away from each other, known as the Hubble expansion. The observations show that galaxies are indeed moving away from each other, suggesting that the universe is expanding. This expansion is supported by various lines of evidence, including the cosmic microwave background radiation, the abundance of light elements, and the distribution of galaxies.
Furthermore, large-scale measurements of the expansion rate, known as the Hubble constant, have been consistent with an accelerating expansion. This discovery led to the formulation of the theory of dark energy, which is believed to be the driving force behind this accelerating expansion.
Option B, "The universe has completed its expansion," is not the most likely outcome because there is no evidence to suggest that the expansion will stop or reverse in the foreseeable future.
Option C, "The universe will start shrinking soon," is not supported by current scientific understanding. The expansion of the universe, driven by the ongoing presence of dark energy, is expected to continue and possibly even accelerate.
Option D, "The universe is already shrinking," is also inconsistent with observational evidence. The expansion of the universe has been clearly observed, and there is no indication that it has reversed or is in the process of reversing.
Therefore, based on the current scientific understanding and observational evidence, Option A, "The universe will continue to expand," is the most likely outcome according to scientists.