resurgance2001 said:Did they simple plot the distances against recession velocities in the normal way but obtain a graph that was not a straight line?
Scientists use a variety of methods to measure the expansion of the universe, including observing the redshift of distant galaxies, studying the cosmic microwave background radiation, and analyzing the brightness and distance of Type Ia supernovae.
The primary evidence for accelerating expansion comes from observations of Type Ia supernovae, which are used as standard candles to measure the distance to faraway galaxies. These observations showed that the supernovae were fainter than expected, indicating that the expansion of the universe is accelerating.
Scientists ruled out other explanations for accelerating expansion, such as the presence of dark matter or a cosmological constant, by carefully analyzing and comparing data from multiple sources, including observations of the cosmic microwave background and the large-scale structure of the universe.
Dark energy is believed to be the driving force behind the accelerating expansion of the universe. It is a mysterious, repulsive force that counteracts the gravitational pull of matter and causes the expansion of the universe to accelerate over time.
The discovery of accelerating expansion has revolutionized our understanding of the universe and its evolution. It has led to the development of the current model of the universe, known as the Lambda-CDM model, which includes dark energy and dark matter as key components. It also suggests that the universe will continue to expand at an increasing rate, eventually leading to a "big freeze" where all matter is too far apart to interact and the universe becomes a cold, dark place.