The Evidence for Modern Physics: How We Know What We Know Season 1 Episode 22 Measuring the Size and Age of the Universe

The Evidence for Modern Physics: How We Know What We Know is an educational series that explores the history and science behind some of the biggest questions and discoveries in modern physics. In season 1 episode 22, titled "Measuring the Size and Age of the Universe," the focus is on the techniques and technologies that astronomers and physicists use to determine the age and size of our universe.

The episode starts with a question: how old is the universe? To answer this, the program takes a close look at the cosmic microwave background radiation, which is the leftover radiation from the Big Bang. Through studying the patterns and fluctuations in the radiation, scientists can estimate the age of the universe to be around 13.8 billion years old.

But determining the size of the universe is a bit more complicated. The show explains that there are a few methods that astronomers use to estimate the size of the universe, including trigonometry and the expansion of the universe. Using the parallax method, astronomers can measure the distance to nearby stars and then use those measurements to create a map of the Milky Way. This map allows them to estimate the size of our galaxy, but it doesn't help us determine the size of the entire universe.

The program then delves into the concept of redshift, which is the apparent shift in the frequency of light from a source that is moving away from the observer. This phenomenon is due to the Doppler effect and is used by astronomers to measure the distance to faraway galaxies. By measuring the redshift of the light emitted by distant galaxies, astronomers can determine how fast they are moving away from us.

This leads to the discovery of the Hubble constant, which is the rate at which the universe is expanding. By knowing the Hubble constant, scientists can determine the distance to faraway galaxies and estimate the size of the universe. The episode explains that the current estimate for the size of the observable universe is around 93 billion light-years in diameter.

But the program doesn't stop there. It also introduces the concept of dark matter and dark energy, which are two mysterious substances that can't be directly observed but are believed to make up a large part of the universe. The show explains how these entities factor into our understanding of the age and size of the universe and how ongoing research is working to shed more light on their properties.

Finally, the episode concludes by emphasizing the importance of these measurements for our understanding of the universe and our place in it. By studying the age and size of the universe, scientists can better understand the origins of our universe and the evolution of galaxies and stars. It's a fascinating glimpse into the cutting-edge science of modern physics, and an excellent example of how we use evidence to expand our knowledge of the universe.