S2 E6: Earth Formation According to Science

Season 2 of Spirit-Led Hope looks at the origin story of our universe and life from both the naturalistic and Christian perspective. In this episode, Glenn continues with the naturalistic perspective of how the Earth was formed.  Because this is a high-level view, only basic scientific principles are referenced.

This episode has a transcript. If your podcast player does not support transcripts, please go to the podcast section of https://spiritledhope.com/ . 

Transcript

S2 E6 TRANSCRIPT

EARTH FORMATION ACCORDING TO SCIENCE

INTRODUCTION

Hello everyone and welcome to Spirit-Led Hope. My name is Glenn Erichsen, and in this episode, we are talking about:

THE FORMATION OF THE EARTH ACCORDING TO SCIENCE

In the last two episodes we looked at how the universe began according to naturalistic science, and now we get closer to home and talk about the formation of the earth.

In preparing for this episode, I noticed on my bookshelf that I had a college textbook from a course I took on Earth science. I know this makes me sound old, but that book was written almost 50 years ago. I was curious to see how much of our understanding of the Earth’s formation has changed in the last few decades.

I found that many of the questions in my textbook, are still unanswered. This is not surprising. No humans were around when the Earth was formed. Anything we know scientifically about the Earth must be inferred from empirical evidence combined with theory.

Interestingly, we are learning more about the formation of the Earth because of our advances in telescopes. We can now detect other planets and observe how some of them are formed. This helps us learn more about how our planet began.

We must keep in mind that our scientific knowledge changes as more theories are developed, and more data comes in. This means that what I am presenting in this Season, is subject to change. But I am trying hard to summarize the scientific viewpoint with the most current theories.

THE BEGINNINGS OF THE EARTH

When we talk about the formation of the Earth, we start with the formation of the solar system. The sun and the planets that we know today, all formed at about the same time…about 4.6 billion years ago.                                           

In the last episode we talked about how some dying stars explode and eject heavier elements into the universe. These heavier elements mix with lighter elements, like hydrogen and helium, and form gigantic clouds of interstellar gas and dust. These clouds are called nebula.

It is believed that shock waves from a nearby exploding star (that is a supernova), cause nebulas to become gravitationally unstable and collapse upon themselves. During the collapse, angular momentum of the system is conserved, and the nebula becomes a somewhat flat, rotating disk of particles, with most mass in the center.

If you do not know what I mean by conservation of angular momentum, think about an ice skater who starts spinning slowly with her arms spread out, and then pulls in her arms. What happens? She starts spinning very rapidly. Something similar happens in the nebula. When the nebular starts collapsing, its rotation increases. This is why planets rotate around the sun.

As this disk rotates, gravitational attraction is acting among all the particles. As a region becomes more massive, more particles get drawn to it. Most of the particles fall towards the center but clumps also begin to form in the disk itself. Because gravity keeps pulling material in, the center eventually becomes so large, so dense, and so hot, that fusion takes place, and a new star is born. The clumps in the disk also continue to grow larger, and they become planets.

What I just described is a high-level view of how most theories say our solar system was born. There are, of course, many nuances and unknowns. With new data coming in from the James Webb Telescope, I suspect many new theories will be made or existing ones modified. 

Let us now think about that early Earth. From theories, and what we can observe in other planets outside of our solar system, it is believed that the early earth was surrounded by a thick opaque atmosphere of gas and dust. If we were standing on that early Earth, and looked upward, it would have been dark because the atmosphere was so thick. And that makes sense, all these particles are being attracted to the Earth by gravity and so the Earth is surrounded by all this interstellar stuff.

Interestingly, geological data indicates that the early Earth was also covered in water. The origin of that water, however, is up for debate. I read many theories about this. For a long time, there was a belief that water came from outside the Earth in the form of comets and meteoroids. That theory seems to be falling out of favor because the data looks less likely to support it. It will be interesting to see where that debate heads. 

Also, keep in mind that there were no mountains on the early Earth because plate tectonics had not yet begun. We will get to that. So, if we were standing on that early Earth, it would have been dark, wet, and featureless.

THE MOON

One thing we have not talked about yet is the moon. As astronomy advanced, most scientists could not figure out why the Earth has the moon it does. Eventually, the most predominant theory stated that the early Earth was impacted by another body about the size of Mars. In this collision the Earth took on more mass and another piece was ejected and became the moon. The collision also modified the rotation rate of the Earth.

This scientific theory is now the most accepted one. One of the big reasons it is accepted is because in 1969, rock samples were brought back from the moon. For those of you my age or older, you may have watched live, like I did, Neil Armstrong taking his first step on the moon. The moon rocks brought back by Armstrong, Buzz Aldrin, and Michael Collins, confirmed that the moon and Earth did not form together. Measurements and calculations also indicate that the moon is moving away from the earth, which implies that it at one time contacted the Earth.

We should keep in mind that conclusions like this are based on circumstantial evidence. However, the evidence does seem to be strong enough that the collision theory is the most predominant theory of our moon’s formation.

I find it interesting how important our moon is for sustaining life on Earth. The rotational rate of the Earth, the stability of its tilt, and the ocean movement due to tides, are all affected by the moon. Many theorists argue that without the moon, chances for life on Earth would be greatly reduced. 

There have been many computer simulations done on how the moon struck the Earth. What these simulations show is that only a certain angle of impact and mass of colliding object could replicate what we see today. Knowing how important the moon is to life, and how unlikely it was for Earth to have a moon like ours, is often cited by Christians as more evidence of fine-tuning done by a Creator. This is like the fine tuning of initial conditions I mentioned in the last episode. Of course, if you are a naturalist, then you simply accept the good fortune that chance gave us.

AFTER THE MOON

The collision that formed the moon would have been dramatic. Most likely much of Earth’s existing atmosphere would have been blasted into space, along with much of the surface water. No one really knows for sure all the details. 

However, the data and theories indicate that water was still present after the collision. Because the collision would have generated massive amounts of heat, most theories point to a large amount of steam in the atmosphere. Eventually, about 3.8 billion years ago, the temperature at the surface of the Earth dropped below the boiling point of water, and the steam condensed into rain. This is the time at which the ocean basins were filled with water.

The conditions on Earth are just right for maintaining an ocean. If the Earth were too small, there would not be enough gravity to keep the water from leaking into space. If we were too close to the sun, the oceans would boil away. And if we were too far away from the sun, the oceans would be solid ice. Not only do these conditions affect the Earth’s ability to have an ocean, but they also affect the ability to sustain life.

It is at this point in Earth’s history that something remarkable happened. But we are going to wait until next episode to talk about it in more detail. It is in this era, about 3.7 to 3.8 billion years ago, that life on Earth began. I mention it now because we have just seen, over this and the prior two episodes, what an amazing sequence of events have occurred. We had the material of the universe spring into existence. We have seen stars created and stars exploding. We discussed the Earth condensing out of interstellar dust, and a fortuitous collision that shook the Earth and created the moon.

All these things that we have discussed up to now somehow generated the conditions for life to begin. Remember, in this episode we are viewing the formation of the Earth according to naturalistic science. And this account must accept that everything that happened for life to begin in this era, was undirected and by chance. That is naturalism.

All right, let us get back now to the formation of the Earth. Prior to about 3.4 billion years ago, the Earth was covered with water. It is at this time, about 3.2 to 3.3 billion years ago, that land began to emerge. This was due to volcanic activity and plate tectonics.

I think most people have heard of plate tectonics. This is the understanding that the Earth’s rocky outer shell is made up of a few sections, called plates, that float on the underlying molten material. These plates can collide with each other. In some cases, one plate may get pushed under a neighboring plate, and this is called subduction. This is happening close to where I live in Washington State.

Plate collisions can result in mountains and earthquakes. The Himalayas, for example, are formed by colliding plates. As the plates collide, they push up these huge mountains. Unfortunately, the Seattle area where I live is predicted to have a massive earthquake sometime in the future due to plate subduction. We call that, in anticipation, The Big One.

You may be wondering what happens to a tectonic plate if it is pushed under another one. Well, that rock eventually gets pushed down far enough where it melts and is reabsorbed into the earth. There are also places on the Earth where new material is added to a plate. An example of this is in the middle of the Atlantic Ocean.

It is easy to see that South America and Africa would fit together like a jigsaw puzzle. This is because they were, at one time, connected. But due to the movement of the plates on which they rest, these continents moved in opposite directions and new plate material is formed as they move apart. And this new plate material is formed on the seafloor between the two continents. 

This is not just a theory because with modern technology we can measure how fast Earth’s landmasses are moving. On average they are moving about 0.6 inches a year. What does that mean? Well, that is roughly the rate at which your toenails grow! There is a visual for you! Watch your toenails grow and imagine South America moving at that rate! Or do not do that!

There is one more event in the formation of the Earth I want to mention before ending this episode. We have already discussed how the early atmosphere of the Earth was thick and opaque. We then mentioned that the collision with the moon would have ejected much of the atmosphere, and then we said there were large amounts of steam vapor. I did not mention this, but we also know that gases, like carbon dioxide and nitrogen were present in the early atmosphere.

Many models of the early Earth’s atmosphere indicate that up to about 2.5 billion years ago, the atmosphere was primarily translucent and not transparent. Imagine something like a thick fog. Under these conditions, light from the sun can be present, but you cannot see the sun. That is translucence. Those were the conditions on the Earth until what is called the “great oxygenation event.” Sometimes you will hear it called “the great oxidation event,” or simply the GOE. It was the great oxygenation event about 2.3 to 2.5 billion years ago that made the atmosphere look like it does today. Transparent, so that we can see through it. But how that happened, needs to wait until the next episode.

CLOSING

At this point, we have a good idea of how the basic Earth was formed. We have land, water, a foggy atmosphere, and I gave a brief spoiler by saying that life has already started. In our next episode, we will continue with naturalistic science and look at the beginning and development of life on Earth.

As always, if you have any comments, suggestions, or questions, please email me at glenn@spiritledhope.com, or simply use the Contact Form at spiritledhope.com. That is spiritledhope.com.

As you go about your day:

May the God of hope fill you with all joy and peace as you trust in him, so that you may overflow with hope, by the power of the Holy Spirit. 

Until next episode, take care.