The Science of Everything Podcast - Episode 11: The Origin of the Universe

Episode Date: December 9, 2010

An overview of the chaotic inflationary theory for the origin of the universe, including a discussion of the inflaton field, quantum fluctuations, spontaneous symmetry breaking, and the zero net energy of the universe. Also includes a discussion of multiverse theory and the fine-tuning paradox.

You're listening to The Science of Everything podcast, and this is your host, James Fodor. In this podcast, I discuss a wide variety of topics in natural and social science, attempting to better understand the world in which we live. This is episode number 11, and the topic for today is the origin of the universe. So in this episode, we're going to look at, well, how the universe came to be. And particularly, I'm going to take the approach from a very interesting model called the chaotic inflation theory of the origin of the universe. I think it provides a very useful way of looking at how the universe could have come into existence essentially from nothing.

It is of course not the only model for the very origin of the universe, but I think it's probably one of the leading candidates, and certainly if everything I say today is not exactly correct, then probably I think it is at least on the right track. And so without further ado, let's get into it. First of all, I want to discuss the standard Big Bang model, because when I say the origin of the universe, most of you probably automatically think back to, well, isn't it the Big Bang? And yes, that is true. However, the Big Bang model itself mostly talks about the very early development of the universe,

not actually the actual origin itself of the universe. So you can think of it like the Big Bang talks about the development of the universe as if it were a fetus, or a developing child, from embryo to fetus to newborn, but it doesn't really talk about conception itself, like the very origin of life itself. That's what I hope to address in this podcast. So, the Big Bang model essentially starts with the observation

that all of the largest structures in the universe, like galaxies and clusters of galaxies and stuff like that, are moving away from each other, and that the speed at which they are moving away from each other is proportional to their distance there, so that farther away galaxies are moving away from a, at a faster rate than closer galaxies. And if you do the math and work all this out,

it turns out that this observation is consistent with the fact that the universe is expanding. And this isn't the only piece of evidence for the expanding universe. There are many others. But the Big Bang model is built upon this as one of the core observational pieces of evidence. The Big Bang model essentially takes that idea of, well, if the universe is expanding now, what happens if we extrapolate that back into the past? well the universe must have been contracting, it must have been smaller in the past. And so if we continue to extrapolate that backwards,

we find that the universe was once upon a time, about 13.7 billion years ago, in fact, according to current estimates, the universe was essentially all compressed into a single point or a singularity of almost infinite density and pretty much zero volume, and that that singularity expanded, sort of exploded in a Big Bang and formed the universe as we know it today. And that's what the Big Bang theory really talks about.

You know, it goes through all the different stages after that initial explosion and talks about how different types of matter formed and then eventually you get stars and galaxies and all that sort of stuff. I'm not really going to focus on that today because I want to focus on what happened before the Big Bang. How did the Big Bang actually occur? So the origin of the universe itself. Anyway, so that's a very brief introduction to the Big Bang,

model, and I will do a later podcast talking more about the Big Bang itself, but the key points are that it was, the Big Bang refers to the origin of the universe, so matter, space, even time, pretty much everything that we associate with existence, from a single singularity about 13.7 billion years ago, and everything just expanded out from that. All right, now let's move into the inflation model of how the Big Bang sort of occurred. But before we do that, another basic, uh, that I need to explain is a field. Now you've probably heard the term field used before, like a gravitational field, an electromagnetic field, something like that. But a field is actually just a physical quantity, so a number, or sometimes a vector, but just think of a number for now,

associated with each point in space-time. A field can generally be thought of as extending throughout the whole universe, but in practice we're only interested in the strength of a field in a particular specific location, because generally the strength of a field decreases with increasing distance from the object. So think of an electromagnetic field. Technically speaking, the electromagnetic field, say, of the Earth, or the magnetic field of the Earth, extends throughout all of space, all of the universe. But beyond a certain point, it gets to pretty much zero. So we don't usually worry about the gravitational field of the Earth, say, in the Andromeda Galaxy.

It's just not worth considering. So similarly, any electromagnetic field or any type of field extends through. out all of space technically, but generally we're interested in the values of that field at a particular localized region. And so when I say a field is a number associated with a given point in space time, it usually just, that number usually just refers to the strength of some interaction that occurs. Like, for example, the strength of the magnetic field of the Earth, just at any point, just refers to the force that's going to be exerted upon moving charged particles when they

are at that location. the force of the gravitational field of, say, the sun would just refer to the strength of the gravitational attraction on any mass placed at that point. And so the further away you move from the sun, the lower the value of the field will be. And so the less attraction there will be between the sun and whatever massive object you've got there. So a field, it's not a real object. It's just an abstraction used to explain or refer to the strength of various forces and interactions at different points in space. Okay, so the reason I needed to explain that concept of a field is because crucial to inflationary theory is the concept of the inflaton field. That's I-N-F-L-A-T-O-N-I-N-Inflat-on field.

So what is an inflat-on field? An inflat-on field is a hypothesized special type of field that existed prior to the Big Bang. So I want to clarify language here. When I say prior to the Big Bang, it's questionable what that even really means because did time exist prior to the Big Bang or how can you have something before the Universe.

It's hard to really explain in ordinary language or even understand what we mean by prior to the Big Bang. It's not really, we don't know exactly, you know, was there time prior to the Big Bang, or questions like that are kind of getting into metaphysics. So don't try and put too much of a literal interpretation upon words I use, like prior to the Big Bang or things like that. Just sort of go with it. Because a lot of these models are highly mathematical in nature,

and so when you translate them into words, it doesn't always work completely well. it can be a little fuzzy, a little hazy as to what exactly you mean. But I think hopefully by the end of this podcast, you'll have a general idea of inflationary theory in how the universe could have come into existence. So let's just move on from here. Back to the inflaton field. So it's hypothesized that this inflaton field

may have existed prior to the Big Bang. Now we haven't yet observed the inflatron field, but for a variety of theoretical reasons, physicists think that it may well exist. And we're looking for it in the new generation of particle accelerator. So hopefully we'll be able to have a more solid evidence for the existence of the inflaton field pretty soon. Now, associated with each given point in the inflaton field is a given value of energy. So you can think of it as, you know, each point in the inflaton field has a certain value,

and that value refers to just kind of an energy potential, kind of like just a position in the solar system is associated with a gravitational potential energy relative to the sun. However, the inflaton field's a bit different to a gravitational field, because it doesn't just diminish with increasing distance away from your object. The inflaton field can be kind of any value in any given place in the universe. And in fact, the value of the inflatant field can fluctuate, it can change from one point in the universe to the other, or one point in space, time or something to another. Because remember, the universe doesn't exactly exist yet, but I'll just call it the universe for, purposes of having a language to speak with. But anyway, so it's kind of, we have no universe,

no space time, but we do have this inflaton field. And the value of this inflaton field can fluctuate at different, quote-unquote, places if you want to use that word. Now, the basic idea behind inflationary theory is that if the potential energy at a given point in the inflatine field reaches a certain critical level, you'll have sort of interesting cascade effects occur. Now, what do I mean by interesting cascade effects? Well, essentially, the inflation field, just like any other field, kind of wants, in inverted commas, because it doesn't really want anything, but I'll use the word, it wants to minimize its energy. It tends to minimize its potential energy. So if, for reasons that I'll explain later on, the potential energy of the inflaton field

just increases at a particular point, the inflaton field will tend to, the value of the field will tend to diminish in order to minimize that potential energy at that point. But in order to achieve this, the inflaton field has to kind of expand space time. It stretches it. It exerts a sort of anti-gravity force that causes a rapid expansion of space time. Now, you might ask, why does it do that? That's a very complicated question relating to the internal mechanisms and mathematical models of what the inflaton field actually is. That's way beyond what we can get into in this podcast. But just accept my word for it at the moment, and not really my word, the word of much more intelligent physicists than myself,

that the inflaton field minimizes its energy by causing an expansion of space time. So once we've got that expansion of space time, you can see how we've kind of started a Big Bang. So in this inflationary model, the Big Bang occurs as a result of an unusually high potential energy value of the inflaton field. The inflaton field then kind of reacts to minimize that potential energy,

and in doing so, initiates a Big Bang, initiates an expansion of space time, a rapid expansion. However, there's another fact about the inflaton field, which kind of complicates the picture, and that's that this expansion of spacetime, yeah, it sort of begins to reduce the potential energy value of the inflaton field at that point,

but it does it very slowly. You can think of it as it's kind of, there's a lot of friction in the system. It's very slow to reduce the potential energy inflaton field, so you need a lot, a lot of expansion in order to get the inflaton field back to its sort of normal energy level. And so as long as that friction force dominates the situation, the inflaton field is mostly stuck in place. It's going down a little bit, but not very much.

As long as that inflaton field is above its sort of normal energy level, it's got a higher potential energy. As long as that situation persists, the expansion is going to persist. And so because the friction force keeps the inflaton field from falling, potential energy of it, from falling very quickly, you get prolonged expansion. The inflaton field is kind of stuck in its higher energy level, coming down only slowly, and so you get lots and lots of expansion. And that's essentially how we got the Big Bang

and the Origin of the Universe. The reason it's called Inflation Theory, by the way, is because during this very initial period only to the friction force stopping the inflaton field from diminishing its energy, it's thought that the expansion of the universe accelerated so much that it was many, many, the orders of magnitude faster than the speed of light. It's not just an ordinary Big Bang,

it's a super-duper, extraordinarily rapid stretching of space. But this extraordinarily rapid stretching only occurred at the very, very beginning. Once a certain critical value was finally reached, the inflaton field energy did come down, and the expansion slowed down to the much more manageable rate, which it's proceeding today. So that's what the inflation actually refers to this extraordinarily rapid initial increase in the size of the universe, which was later tapered down to much more modest rates of increase. But the universe is still expanding to this day. Okay, so from this basic model of the inflaton field, we can see that we've got space time.

We've got a universe, but what about matter? Where did all the matter come from? Because the universe is more than just space. There's also stuff in it. Well, from E equals MC squared, Einstein's famous equation, which I've mentioned before on this podcast, you may know that energy and matter are essentially the same thing. Matter is just a congealed form of energy. E, energy equals M, which is mass, multiplied by C squared, which is the speed of light. So energy is essentially convertible into matter.

So when we talk about the origin of matter, all we really need is energy, and from energy we can get matter. So where did all the energy in the universe come from? And the answer is that the energy, which later on became the matter of the universe, came from the inflaton field, because remember, the inflaton field at this particular point has a very high, unusually high potential energy value,

and that slowly come down a little bit as a result of this massive expansion of the universe, but it's still pretty high. What actually happens, though, is that as the universe expands, the potential energy of the inflaton field is high throughout essentially the whole universe now, or the whole area that we're concerned with, not just at this one little point. Originally, the inflotone field was only had this high potential energy value at one particular point. You can think of it as kind of like looking at a landscape, and this one little mountain pokes up in this one little area, but the rest of it's pretty flat. However, if that mountain then expands outwards, just massively increases in size, almost the entire landscape, which kind of represents the universe in this case, is at that high potential energy level.

And what happens when you have a situation like that, and once again, this comes back to the very complicated mathematically. behind all this, but when you do all that math, what happens is that this energy kind of spontaneously converts itself from potential energy in the inflatant field into real energy, the kind of energy that powers our cars and so on, E equals MC squared type energy, and then from energy it later becomes matter. So essentially, what's happening in the inflationary model is that both the space itself and the energy and matter in that space come from, the energy that was embedded in this original potential energy spike of the inflaton field. So that's pretty cool. We've got a universe essentially from nothing, coming just from a fluctuation,

or a high potential energy value in the inflaton field. But of course that just seems to beg the question. Okay, if everything came from the inflaton field, where did the inflaton field come from? Most particularly, where did the high potential energy peak value of the inflaton field come from? And the answer, it turns out, comes back to the Heisenberg uncertain. principle of quantum mechanics. Now, I still have yet to do an episode on quantum mechanics, so I'll cover this in more detail later. But the basic idea of the Heisenberg uncertainty principle is that absolute and total nothingness is unattainable and impossible in the universe. You can't actually have complete nothingness. In fact, if we go out into space, suppose we move far away from

all planets, from all stars, even from all galaxies we go out to, there seems no gas, just complete nothingness. It's still not complete nothingness. What actually exists in such apparently empty areas of space is virtual particles and other transient particles which are continually spontaneously forming and then quickly annihilating each other. And the reason they have to annihilate so quickly is because that way they don't violate the law of energy conservation. These spontaneous births and deaths of particles are called virtual particle pairs, and the whole process is known as quantum fluctuations. So throughout the whole universe,

we're constantly experiencing these quantum fluctuations of particles popping into existence and then quickly annihilating each other. And this may sound, if you haven't heard of it before, completely bizarre, but it has been, apart from being very consistent with quantum theory and various mathematical models, it's been conclusively demonstrated in the laboratory. In fact, the Casimir effect is very interesting.

If we move metal plates close enough to each other, they have to be very, very close, we can actually reduce the size of the space between those plates if we reduce it enough, becomes so small that even virtual particles can't fit in them, and so the virtual particles can't form in between the two plates, and so we actually observe an attractive force between the two plates, which is occurring because virtual particles can appear outside the plates, so on the other side of the two plates, but not in between them.

So the virtual particles kind of push the two plates together. that effect has been observed and reliably reproduced in laboratories and is one of the many powerful pieces of evidence for quantum fluctuations so they do exist and we know from quantum theory that as I mentioned before also from the Heisenberg uncertainty principle more specifically absolute nothingness is impossible you always have these quantum fluctuations and virtual particles and other random stuff that's that's there and fields and other things there's always something there there's never just nothing and so one interpretation of this is that empty space but filled with fields and virtual particles and quantum fluctuations is actually more likely,

more energy favorable if you want to use that language, than a universe totally devoid of anything. So the right question would not actually be, well, why was there an inflaton field and why were there these quantum fluctuations and other stuff? The question would be, why wouldn't there be such things? Because everywhere we look, we find such things. That just seems to be the way reality is constructed. Now, of course, you could ask why. Is it constructed that way? But that's getting into metaphysics and far beyond the scope of the discussion today. And in fact, even if you somehow devise an experiment where you could get rid of all of these fields and virtual particles, they would spontaneously reappear. They'd spontaneously reform. It's simply, as I mentioned

before, energetically favourable that these things exist rather than not exist. So we don't really need to explain where the inflaton field came from. It would be surprising if something like it did not exist. Now, one thing we might ask, though, is, okay, we can say, well, we've got an inflatant field, but where did this high potential energy value of the inflatron field come from? Because that's where the energy that expanded space and created all the matter and energy actually came from, it came from not the inflaton field in and of itself, but this high potential energy spike at a particular point in the inflaton field.

So where did that come from? That sounds like a pretty odd thing just to have. Well, not so, because once again, this is just another form of a quantum fluctuation. just as virtual particles are spontaneously forming and annihilating in space, so, too, the values of things like fields, maybe a magnetic field, although in this case it's an inflatron field, can spontaneously fluctuate as well, perhaps due to these virtual particles or due to other reasons.

It's just a different type of quantum fluctuation. So you can imagine this, if you can think of the inflatron field as kind of a membrane, just a flat sheet, and this membrane then is constantly fluctuating in a, bits of it might be spiking upwards, bits of it spiking downwards, some of the spikes are small, some of the spikes are big. These spikes represent the potential energy values of the inflaton field at that particular point in the field, and these fluctuations may only last a very short period of time.

Remember, I'm using time in a kind of metaphorical sense here, because we don't really know if there was time. But anyway, they may be very brief, but they still exist. And so we've got this inflaton field fluctuating up and down, and these random quantum fluctuations of the values of the field. all we need is one region, no matter how small, if one region fluctuates sufficiently high such that it has the potential energy level necessary in order to initiate inflation, as I described above, then we can get a universe out of that.

We can get a big bang out of that. And in fact, this very tiny region, because it would expand so much, would come to occupy almost the entire volume of the universe or of the field, because the rest of it would become so small, in comparison to the massively expanded region that it doesn't actually matter how small the initial fluctuation was.

As long as you have that fluctuation somewhere, you can get the inflation and get a Big Bang. So that explains how we got the energy, the high potential energy level of the inflatant field that we needed for a Big Bang. It was just a random fluctuation, and random fluctuations like that are basically guaranteed to happen from the laws of quantum mechanics. Another very interesting sort of application of this inflationary,

chaotic inflection of principle, or theory, is that it can explain the apparent fine-tuning paradox of the universe. The fine-tuning paradox is essentially why is the universe so fine-tuned, or apparently fine-tuned, so that it can have, so that a complex entities such as stars, galaxies, planets, and more particularly human beings and other forms of life, how is it that they can exist? Because you find that if you tweak the laws of nature or the fundamental or constants of nature, even just a little bit in this direction or another, make them higher or lower, like if the speed of light was a bit bigger or the strength of gravitational force was a bit smaller or whatever, there are many, many such constants in physics.

If you change any of these just a little bit, you can run through the models, and it seems that life wouldn't exist. You know, maybe atoms would be unable to form, or stars would be unstable, or things like this, or all elements would be radioactive. Clearly, in these situations, we would not be able to have life, as we know it, or maybe stars would not exist, and therefore we would not be able to have life. So why is it the universe is so fine-tuned that everything's arranged just so that we can have life and other complicated entities? Well, the multiverse hypothesis of inflationary theory explains this. Basically, the idea is that if we assume that there is an inflaton field,

and then it can have experienced quantum fluctuations, and that a quantum fluctuation of the right type can lead to a big bank, essentially the expansion of space, and then the... formation of matter as the inflaton field returns to its base value at that particular point, and so you've got a universe, essentially. If we take that idea, we can actually apply it not just to our universe, but to other universes as well. There's really no reason why that would happen, this quantum fluctuation leading to Big Bang would happen only once. In fact, it could and should happen many, many times, perhaps an infinite number of times, although if you don't

like infinities, you can just say a very large number of times. And each of these universes, because they're kind of randomly formed, that's where they're chaotic, and chaotic inflation comes from. It's kind of chaotic in how all these different universes are forming. But because each universe forms in a slightly different way, with a slightly different value of the inflaton field and all that, you can get different physical constants in each universe. So maybe one universe will have stronger gravity,

another one will have atoms that rapidly decay. All sorts of things can be changed, if the physical constants can be changed. And so some of these universes will be hospitable to life, some of them would not be. Some of these universes, and probably most of them, would be very boring because you'd just have a whole bunch of dead stars or a bunch of atoms, or maybe the universe itself would be unstable. It would immediately collapse or expand into nothingness if, let's say the gravitational force was too strong or too weak. But because there are just so many of these universes,

it is not surprising that at least some of them, or at least one of them, the one in which we live, were so constituted, the physical constants were so arranged that life was able to form. And of course, it is no surprise that we, as intelligent beings, find ourselves in such a universe. Now, this idea of multiple universes might sound a bit far-fetched, but if you actually look into the literature of the origins of the universe, inflationary theory, cosmology, all this sort of stuff, the idea that there may be, also in quantum mechanical theory, The idea that there may be more than one universe is actually not that unusual.

I mean, if you just look at Scientific American, for example, or Wikipedia, you can get all sorts of serious physicists and theories and general articles and so on where people are talking about this sort of thing. So it's not that unusual. There are many different models of cosmology and physics and so on that are fully consistent with multiple universes and, in fact, would predict multiple universes existing, just like in string theory. If you're familiar with that, you'll understand this analogy.

If not, don't worry about it. But in string theory, they hypothesize the existence of 10 or 11 dimensions, whereas we only observe 4. That sounds completely bizarre, but a lot of physicists take string theory very seriously, and so the existence of additional dimensions would not be such an unusual thing. Similarly here, the existence of additional universes, sometimes called bubble universes, is not such a surprising thing. Now, these universes probably we would never be able to come into contact with them, because they're too far away or they're moving away from us faster than,

then the speed of light, or perhaps some other effects prevent us from coming into contact with them. But that doesn't really matter. The point is that they exist sort of out there, quote-unquote, in an abstract sense, that they were produced by the same fundamental physical process that produced our universe. And that's all we need to explain the fine-tuning paradox. If we can just get a large number of universes, then it's not surprising that at least one of those universes, or maybe more than one of those universes, was fine-tuned in such a way that it could form life. Now, you might ask, how can the laws of, or the physical constants of physics, just sort of spontaneously be different in one universe to another?

The way that can happen is through a process called spontaneous symmetry breaking, and this seems to be very well supported in physics, because, for one reason, we would expect from current models, or at least past models, that there would be an equal amount of matter and anti-matter in the universe. But if this had occurred, then all of that would have sort of a nice way. It would not have any matter at all in the universe. It would just all be energy. Clearly that hasn't happened, so there must have been some kind of spontaneous symmetry breaking where more matter formed than antimatter.

And so that allowed us to continue to exist without being completely annihilated. That's just one example of spontaneous symmetry breaking. There are many others that have been observed in various realms of physics. Spontaneous symmetry breaking just refers to the fact that an initial situation could be completely symmetrical. Think of a ball at the top of a hill. Imagine this hill is completely symmetrical on all sides so that it's exactly the same. And imagine you have this ball on the very, very top of the hill,

the very, very point at the top of the hill. This is a symmetrical situation in that the ball could roll down on any side of the hill and it would be completely, it would be completely the same. If you look at this situation from any side, from any angle, it looks the same. There's no particular differences, asymmetries that can be observed here.

But as soon as the ball starts rolling, down the hill, there will be an asymmetry. The ball is no longer at the very center of this structure of the hill. It's more down one side than another side. So the initial situation is symmetrical, but unstable. The ball is just very tenuously balanced at the very top of the hill in the symmetrical situation, but it's not going to remain there. That's an unstable situation. The point of this example is that the slightest perturbing force, even just a random tiny gust of wind or whatever, will push the ball just ever. so slightly in one direction, and then it will, you know, the force of gravity will act on it,

and it will continue to roll in that direction. In this way, symmetry has been broken. The ball is now rolling down one particular direction down the hill. The physical constants of the universe could have come about in such a way. There could have been, each universe may have begun in this unstable situation, unstable but symmetrical situation, but some just random fluctuation, once again probably just a quantum fluctuation of some kind, pushed each universe in a slightly the different direction with different physical constants so that now things were asymmetrical. The universe has different physical constants for different things. Now, once again, this idea of symmetry, what exactly is symmetrical in terms of physical constants?

It's very mathematical in what that actually means. You have to look at the equations to see what we mean by symmetry, but just sort of take the word of smarter physicists in that this sort of process can work. But just imagine that ball rolling down the hill and being pushed slightly in one direction or the other. So that's a good analogy of what spontaneous symmetry breaking refers to. So that process, once again relying on random quantum fluctuations, is how we could get different universes with different physical constants. And if we have different universes with different physical constants,

it's not surprising that at least one of those is suitable for life. So that's the basic outline of the chaotic inflationary model. There are just a couple of additional points that I want to make. One is the conservation of energy. Now, you've probably heard of this before. energy cannot be created or destroyed. So if we're getting all of these universes out of apparently nothing, doesn't that violate the conservation of energy? Well, the answer is no, it doesn't, or at least it needn't be so. The chaotic inflationary model explains how we could get universes

without violating the conservation of energy. The basic idea of how this works is that the positive energy of matter and radiation is exactly cancelled out by the negative energy of gravity. So this is sort of like how if you start with zero, you can get 100 and negative 100 out of that zero without violating conservation of energy. You've still got zero, but you've now divided into positive and negative 100. This is essentially how the universe is. It's got a positive, massive amount of energy in the terms of matter and radiation, and a negative massive amount of energy in terms of gravitational potential energy. These two exactly cancel each other out, or would have cancelled each other out if you sort of could combine them in that way. And so the

whole unit, the total net energy of the universe is zero, and so it does not violate the conservation of energy. Remember that the space of the universe and the matter in the universe, or the energy that created that matter, came about in slightly different ways from the inflaton field. The space of the universe came about as a result of the expansion of the universe that could, as the inflaton field began to fall from its high potential energy level. The matter and energy in the universe, however, came about as that energy that remote. in the inflaton field after a certain critical point was reached, just sort of all the rest of it just went.

So you can think of it like a ball was rolling down a hill, and with the hill representing the potential energy value of the inflaton field, the ball kind of representing the universe, the ball rolls down the hill that's slowly diminishing in potential energy, but not very rapidly. As it's rolling, the universe is expanding, but eventually it gets to kind of a cliff and just falls down. It just goes bang.

So as it falls down, potential energy is going down very rapidly. where did that potential energy go? That potential energy went to the creation of matter and energy. So, all of the energy of the universe came from the decay of the inflaton field, but the initial decay caused expansion, the final rapid decay caused matter and energy. And the mathematics behind that are very complicated, but that's the general idea. Now, you may have heard this idea of negative gravitational energy before, you may not, but you might wonder how does that work. always gravitational energy negative. I mean, we don't usually think of it in that way. Well, once again, it comes back to the mathematics. If you write down the equations, it does work out that gravitational

potential energy is kind of negatively offsetting all the other energy in the universe, but I can give you an analogy that helps kind of explain how that works. Imagine we had a rocket, which was accelerated to the exact escape velocity of the earth, let's say. And so as this rocket moved away from the Earth. So imagine we give it an initial force, an initial push, which accelerates exactly to escape velocity, but after that, the only force acting upon it is the force of gravity. So this means that it's going to be constantly slowing down as it moves farther away from the Earth. So we see what's happening here. The rocket's moving farther away from the Earth. As that happens, it's gaining gravitational potential energy. Its distance from the Earth is

increasing, so its gravitational potential energy is increasing. However, it's kinetic energy, the energy of its velocity is diminishing. It's going down because the Earth's pull on into slowing it down. If the rocket was accelerated exactly to escape velocity, that actually means that kinetic energy would become zero. It would have zero kinetic energy after traveling an infinite distance or after arriving in an infinite distance away from the planet. However, if an object were at an infinite distance away from the planet, say from Earth, it would also have zero gravitational potential energy because at an infinite distance there's no gravitational force acting between them. So at this infinite distance away from the planet you've

got zero gravitational potential energy and zero kinetic energy, if it started off from, if it started off traveling at escape velocity, and therefore it has zero total energy. And that still works. If we brought this object now back from an infinite distance away and somehow came crashing down to earth, it would, what you would see is that it was sort of gaining gravitational energy, at least at first, but it also gaining kinetic energy. But that only happens because we've taken this zero total energy and kind of converted into negative gravitational potential energy and positive kinetic energy. So as the object moves towards the Earth, it gains kinetic energy. In order for that total energy to remain consonant at zero, the gravitational potential energy has to decrease by the

same amount. So that the gravitational potential energy starts at zero, but then becomes negative as the object approaches the planet. And then once again does become zero once the object, just before the object crashes into the planet when all of the energy is now in the kinetic energy. So that's kind of an analogy that maybe helps you understand. understand how gravitational potential energy is actually negative in a sense. It comes more fundamentally, though, from the mathematics of the situation. And so, with negative gravitational potential energy and positive energy in the form of matter and, well, normal energy like radiation, we can have the universe coming out of nothing,

because the total net energy of the universe is zero. And so I just want to kind of summarize a bit here and look at sort of draw back a little bit. What I've outlined here is a self-sustaining multiverse. It's not just one universe, it's a multiverse comprised of essentially the inflaton field, which is fluctuating. Whenever you get a sufficiently large fluctuation in the energy density of this inflatron field, you get a big bang in a universe. And so there are many, many universes in this multiverse, as mentioned before,

all of which probably have different physical constants. But the entire multiverse itself is ever increasing in size, because you've got inflations occurring in all different times as a result of different quantum fluctuations, and constantly changing in a case. chaotic manner, hence the name chaotic inflation. The multiverse is chaotic and it's inflating. This process is also called eternal inflation because it keeps going sort of as a chain reaction and you get a fractal-like pattern of universes if you're familiar with that terminology. The universe as itself, or the multiverses itself in this model is immortal. Each particular

part of the universe may collapse, may form in a big bang and then collapse into a singularity in a big crunch or it may expand out into nothingness. But the multiverse as itself is eternal. It always exists and it continually expands. Now I'll just go over the chaotic inflationary model for the origin of the universe that I've outlined, again, just in very brief terms so hopefully you can get the core ideas. So I'll just read from a quote here, which I think is a very good summary. The inflaton field was the dominant field in the early universe. This field is normally in a low energy state, but because of quantum fluctuations, in one region it spiked to a peak, a very high value of its potential energy. This,

led to an expansion of space-time at alarming speeds, many times faster than the speed of light. As it expanded, however, the inflaton field gradually slid back to its ground state, as it did so dumping out a large amount of energy, the bioproduct of which was matter. This matter then slowed the expansion of the universe to a more reasonable rate. And so, in answer to the question of why the universe came into existence, I offer the modest proposal that our universe is simply one of those things which happen from time to time, as a result of random quantum fluctuations. And that's a quote from a scientific American article that I read.

The universe is simply one of those things that happens from time to time as a result of random quantum fluctuations. That may seem like a very bold proposal, but as I've mentioned here, many physicists are taking this idea and ideas very much like this very seriously. And, of course, inflation theory does require certain assumptions, but it explains a great deal of the universe, many features of that universe from a relatively small number of assumptions.

Basically, we just need the inflaton field and a couple of other things fit into place. A very small number of assumptions, and we get an explanation of why the universe is, for example, why the universe is expanding and why life exists in the universe because of the existence of many other universes. And it also seems to arise naturally from our current theories of physics. We don't really need to change any theories of physics or quantum mechanics or anything in order to have chaotic inflationary theory. It fits very nicely within current models physics. So in other words, it seems very likely that inflation would have occurred in the early universe, and if it did, it would have given rise to a universe much like the one we see today.

So even if the inflationary model that I've outlined here is not completely accurate, I think the evidence at the moment is pointing towards something like it being accurate. The basic idea to reiterate is that you cannot have absolutely nothing. You have to have quantum fluctuations at the very least. That just seems to be the way reality is. If we have the existence of a particular field, the inflatom field, quantum fluctuations under the right conditions, can spontaneously produce a universe. If enough of those universes are produced,

just by random chance, at least some of them will be suitable for life. And we live in one of those universes. So, that's all I have to say about the origins of the universe. If you enjoyed this podcast, please leave a favorable review on iTunes or any other podcast aggregator side of your choice. Please visit the website, which is the Science of Everything.

Dot Podbean.com My email address is Fods12, F-O-D-S-1-2 at gmail.com. Please feel free to send me feedback or any other things you'd like to say about the podcast. And if you haven't subscribed,

please do so. You can find the podcast on iTunes. Hope you enjoyed this episode and I'll speak to you next time.