Everything Everywhere Daily: History, Science, Geography & More - The Big Bang Theory

Starting point is 00:00:00 Throughout history, philosophers have pondered how the universe began. And for centuries, it was just that, pondering. It wasn't until the 20th century that enough evidence began to accumulate about the universe that it was possible to establish a reasonable theory. Ultimately, in 1927, a 31-year-old Catholic priest from Belgium, using the latest scientific discoveries, proposed a theory to explain the origins of the universe. Learn more about the Big Bang theory, how it came about, and how we think it happened, on this episode of Everything Everywhere Daily.

Starting point is 00:00:30 What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. The origin of the universe is a pretty heady thing. It should come as no surprise that it's a question that philosophers have asked for thousands of years.

Starting point is 00:01:17 Aristotle believed that the universe was immortal. It had no beginning and simply always was. Aristotle's view was simply a belief that he held without any real evidence. It seemed reasonable to him, so we went with it. While Aristotelian philosophy held sway for centuries, his belief in the origin of the universe did not. All three of the major Abrahamic religions, Islam, Judaism, Christianity, hold that the universe had a definite begin. In the Middle Ages, a host of Christian Islamic and Jewish philosophers pondered the question of a universe with a finite age. The Jewish philosopher Maimonides claimed that it was impossible to prove that time, and hence the universe, was finite or infinite. The Greek Byzantine philosopher John Philippanus, the Arab philosopher Al-Khindi, the Persian philosopher Al-Gazali, and the German philosopher

Starting point is 00:02:04 Emmanuel Kant have all pondered the question of a finite and definite origin to the universe. In 1225, the English theologian Robert Grosotestey actually came close to the modern theory when he posited that the universe began with an explosion. Even Edgar Allan Poe threw his head into the ring in the 19th century, claiming that everything originated from a single primordial particle. The point of all this is that pretty much every civilization and a great many philosophers over the centuries have pondered the question of the origin of the universe, with a bent amongst the monotheistic religions towards a universe that had a finite origin.

Starting point is 00:02:39 Still, all of them were just trying to make logical arguments based on zero evidence of how the universe actually worked. It wasn't until the start of the 20th century that there was a profound revolution regarding our understanding of how matter, energy, and the universe actually behaved. The ultimate development of the Big Bang theory required not just an understanding of what was happening at a cosmological level, but also an understanding of things at an atomic and subatomic level. One of the biggest theoretical underpinnings of the Big Bang theory was Einstein's theory of general relativity, which held that the universe couldn't be static. In fact, Einstein initially thought that he was wrong, but it turns out that he was actually right. The thing that really laid the foundation for the development of the Big Bang theory was the observation of red shifted light from distant nebulae. The first observation was in 1912 by the American astronomer Vesto Sifler. Edwin Hubble discovered that many of the observations made by Sifler,

Starting point is 00:03:35 weren't of objects in our galaxy, but rather were much further away. There were galaxies of their own, and the Milky Way wasn't the totality of the universe. And he also discovered that the red shift of the galaxies increased with its distance from Earth. Here I should explain precisely what red shifts and blue shifts are, because it's the fundamental thing that helps explain not only the Big Bang theory, but also a great deal of contemporary astronomy. Light is a wave, just like sound, and you're probably familiar with the Doppler effect, which is when an object moving towards you makes a higher pitch sound, and when it moves away from you, it makes a lower pitch sound, like a car or a train or a siren. Even though the sound coming from the source is constant, because it's moving

Starting point is 00:04:18 relative to you, it sounds like it's changing. When the object is moving towards you, the sound waves get pushed together, resulting in a higher pitch. When it moves away, the sound waves get pulled further apart, resulting in a lower pitch. Light waves behave in exactly the same way. However, instead of changing pitch, they change color. A light emitting object moving towards you will have light waves push together, resulting in shorter wavelengths, moving it towards the blue end of the spectrum. By the same token, if something is moving away, the light waves will be elongated, making the light waves longer, moving it to the red end of the spectrum. We actually know with a great deal of precision exactly what wavelengths of light are emitted from gases like hydrogen

Starting point is 00:05:01 and helium when they're heated. We can then measure what light we observe. We can then measure what light we observe, compare it to what it gives off under laboratory conditions, and then calculate the direction something is moving away or towards us, as well as the velocity. When it was discovered that light from the most distant galaxies was redshifted, it was groundbreaking. The galaxies weren't stationary, but were in fact moving and moving away from us. In 1922, Soviet physicist Alexander Friedman used Einstein's equations to prove a theoretical model for an expanding universe. However, because he was in the Soviet Union and then died in 1925, much of his work wasn't known to the rest of the world. In 1927, George Lometra independently made the same discovery as Friedman.

Starting point is 00:05:45 Also, he showed the mathematical relationship between the velocity of galaxies and their distance, which was later independently discovered by Hubble. In other words, the further way the galaxies were, the faster they were moving away from us. In 1931, he wrote papers that made two important contributions to the subject of this episode. He proposed that the expansion of the universe was in fact accelerating, and if you were to trace everything backward, you would eventually reach a point where the entire universe was what he called a primeval atom. He also called it the cosmic egg. George Lemetra is widely considered to be the originator of the Big Bang theory. Lemaître was not the sort of person you'd normally expect to be making theoretical proposals for the origin of the universe. George Lemaître

Starting point is 00:06:28 was a Jesuit Catholic priest who studied for the priesthood. while working on his PhD. His idea that everything in the universe expanded from a single point was not well received at first. However, it was actually his colleagues from the physics world that rejected it, not the religious ones. Many physicists actually thought the idea seemed too religious. One of the alternative theories that was floated in the years after was the steady-state theory by English astronomer Fred Hoyle. Hoyle held that the average density of the universe remained stable and more matter was created as the universe expanded. He inadvertently coined the term Big Bang in a 1949 interview he conducted with the BBC when he said, quote,

Starting point is 00:07:09 these theories were based on the hypothesis that all the matter in the universe was created in one Big Bang at a particular time in the remote past, end quote. Over time, competing theories for the beginning of the universe began to fall by the wayside. One of the biggest discoveries that confirmed the Big Bang theory was the discovery of cosmic microwave background radiation in 1964. This background radiation which permeates the universe is actually left over from the Big Bang. This is exactly what had been predicted and offered an empirical solid evidence for the theory. Eventually, supporters of the steady state theory fell aside as the evidence piled up, and the term Big Bang began to be used more prominently to describe the theory in the 1970s. The Big Bang theory has proven to be a robust explanation for the abundance of light elements,

Starting point is 00:07:57 the distribution of background radiation and the structure of the observable universe. So far, I've been talking about the Big Bang Theory in the abstract, just referring to it. So what exactly does it entail? What I'm going to go over quickly is the current most widely held belief based on the current evidence. The evidence doesn't just come from astronomy, but also the world of quantum and atomic physics as well. Everything is believed to have started with a singularity about 13.8 billion years ago. Everything in the entire universe was condensed down to a point. All the stars, all the galaxies, all the matter, all the energy.

Starting point is 00:08:39 What happened is often called an explosion, but it actually wasn't. An explosion is an expulsion of matter into space. This was an expansion of space itself. And this is a really hard concept to wrap your head around because it's something that we can't relate to with our day-to-day relationship with the universe. We have no idea why the singularity expanded. We have no idea what came before the singularity. As far as we know, there is no way to know. However, there are guesses as to what immediately happened after the expansion began.

Starting point is 00:09:14 And when I say immediately, I do mean immediately. an incredible amount happened in just the first second. When the singularity began to expand, things were incredibly dense and incredibly hot. It was so hot and so dense that we really don't even have the physics to understand it. At 10 to the negative 36 seconds, a trillionth of a trillionth of a second, it's believed that all the fundamental forces in the universe may have been merged into one. Within the tiny fractions of a second after that, the fundamental forces may have separated, subatomic particles such as gluons and then things

Starting point is 00:09:51 that make protons and neutrons appeared. During the first, second, space was expanding faster than the speed of light. This didn't violate the laws of physics because it wasn't something going faster than light. It was space itself expanding. Temperatures dropped quickly simply because space was increasing quickly. The subatomic particles eventually cooled and began forming protons and electrons, which themselves joined to form hydrogen and small amounts of helium. Eventually, over hundreds of millions of years, hydrogen began to coalesce into stars, and then they began to form galaxies. That is a really, really truncated version of everything, but the important thing to know is that in the very first tiny, tiny fraction of a second, space expanded very

Starting point is 00:10:36 rapidly. In terms of a linear distance, it may have gone from one nanometer to 10.6.7,000, light years in diameter before 10 to the negative 32 seconds had elapsed. After the initial expansion, things slowed, but never actually stopped expanding. The Big Bang theory has survived because it continues to explain so much of what we observe in our universe. However, it doesn't explain everything, and there are observations that will require modifications to the theory. One thing that still can't be explained is the imbalance between matter and antimatter, which I've covered in a previous episode. There had to be some reason for the imbalance, and there really isn't any proof of anything yet to explain

Starting point is 00:11:17 the imbalance one way or another. Another wrench thrown into things are the recent observations made by the James Webb Space Telescope. The web can see across almost the entire observable universe, which means observing some of the oldest galaxies in the universe. What they found is that there are galaxies that are far larger and older than the current theory suggests should be possible. And of course, there's also the problem of dark matter and dark energy, which may or may not even exist and the gravitational anomalies that it may explain. None of this means that the Big Bang theory needs to be completely overturned, but it does mean that as we discover more, the theory needs to be modified to fit the new discoveries.

Starting point is 00:11:55 The Big Bang theory has proven to be a successful explanation for the observations we've made across multiple fields and physics. Even if the new discoveries can be fit into the theory, there will still be things that will be beyond our limits of understanding, because that is just the nature of. of the universe. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Thor Thompson and Peter Bennett.

Starting point is 00:12:22 I just want to thank everyone, including the show's producers, who support the show over on Patreon. If you'd like to support the show, just head over to patreon.com, which is currently the only place where you can get show merchandise. Also, if you want to talk to other listeners about the show, head over to our Facebook group or Discord server, both of which have links in the show notes.

Everything Everywhere Daily: History, Science, Geography & More - The Big Bang Theory

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