Welcome back everyone! I'm sorry that I haven't updated in awhile (part lack of material, part being busy with everything else). So I've been thinking recently about the end of the universe, not the depressing kind of thinking either. More along the lines of modern thinking relative to how the universe moves within time and space. Now, there is a classic poem that hopefully will be familiar in some aspects. This is Fire and Ice by Robert Frost.
Fire and Ice
Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
As wonderful as this poem is in the literary sense, it actually has some real-world implications. This poem is very apt to the universe's motion within spacetime. We know from studies of redshifting that every galactic body is moving away from us at an accelerating rate, but not in the conventional sense. To clarify, let me explain redshifting and the "conventional sense" of expansion.
Redshifting
The concept of redshifting is a bit tricky to understand without background knowledge of basic light and wave physics. But let's make it easy here. Light as we know it travels in two forms, depending on the experiment you perform. The first form is packets of light, known as "quantas" of light (hence where the term Quantum Physics was derived). These behave as singular particles, and have been known to experimentally exist. The quanta of light has a specific amount of energy which then defines other properties such as the color and behavior of the light. The second form is in a wave (think like a repetitive ocean wave), and travels as such. The size (amplitude) and frequency (how small the individual waves are) of the wave determine roughly the same properties as the energy of a quanta does. Redshifting concerns the second form of light as the properties of a wave can actually be affected by something that quanta cannot: the speed and direction of the source. Here's the easiest way to understand this. If you have ever paid attention to the sound of a firetruck as it moves past you with sirens blaring, you will probably be familiar with hearing the siren as higher in pitch as it comes towards you and then lower as it passes you. That is called the Doppler Effect and in more technical terms it means that the frequency of a wave (the pitch of the tone for a sound wave or the color of the light in a light wave for example) can be affected by the speed of the source in which the wave is emitted from. For sound it is fairly easy to change the pitch as sound moves through air at about 330 m/s whereas light moves through space at about 300 million m/s (a factor difference of approximately 10^6). A truck moving at 20 m/s affects the frequency of sound way more than the frequency of light. Make no mistake, the speed of the source does not affect the speed of the light, but it does affect the frequency. The frequency of sound affects the pitch (how high or low), and the frequency of light affects the color (a slower frequency means larger waves and more red color. A faster frequency means shorter waves and a more blue color.). There are other types of waves as well that are changed in different ways by the frequency, but here we shall only consider light.
So what is redshifting then? Redshifting is merely another name for the Doppler Effect changing the frequency of light. This means when a source that emits a frequency of light moves away from the observer (e.g. us) the frequency of the wave decreases and becomes more red. So how does that help us? Well it is a very useful method to find out how fast something moves away from us. If the color of the light of a star or galaxy remained the same, we could say that the star or galaxy did not move relative to us. However we have observed that for many interstellar objects they actually seem to be redder over a period of time. What this means is that many stellar objects are moving away from us! But the interesting thing that the scientific community has noticed is that the degree at which these bodies become redder is not constant, but increasing, meaning that objects light frequency does not increase by a fixed amount, but an increasing one! This all amounts to the fact that the universe around us moves away from us at an accelerating rate. This is what redshifting is and why it is important.
Expansion
Now's the more difficult part, which is understanding what I mean by expansion. I will have to explain this better in another post as there are other important concepts to define but I will explain how this relates to the poem at least. When we normally say expansion, we mean things are moving away from each other in space. This would imply that all objects in the universe move away from each other in a fixed space. Strangely this is not true because it is not under this concept of expansion. Rather, it is not the bodies expanding in a fixed space, but fixed bodies in an expanding space! This is a strange concept to absorb, because it is hard to imagine that the bodies are moving, but not moving. It sounds like some really badly-worded Star Wars quote, but let's make it easier shall we? Imagine that you have a balloon, and you draw two dots on it with a marker maybe an inch apart. Now you blow up the balloon. The dots have not physically moved on the balloon, have they? No of course not! But you must admit that upon visual inspection they are definitely further apart from each other. That is because the actual space that the dots are in has expanded, which pushes them away from away from each other. If you replace the dots with two stars and the balloon with the universe, that is something close to what I am trying to explain. The universe itself is expanding, but the stars themselves are not actually moving away from each other (to get a little more technical, it is the dark matter and energy in the universe that expands in a very strange way that we don't entirely understand).
So what's the point of all this? Well let's take a look at the poem mentioned in the beginning of this post! When the universe expands, it also cools down (not as much radiation reaches the surfaces of planets, etc.). So when Robert Frost mentions the world ending in ice, it actually is somewhat apt to one way that the world (and the universe) is hypothesized to end, which is that the universe will expand so greatly that it will cool beyond the point that is sustainable for everything. So it seems that Robert Frost was not only a celebrated poet but also an unknown and unintentional physicist! The other concept of ending in fire is also apt, as there is another theory that the expansion of the universe will soon slow down to the point where the intra-galactic gravitational forces will pull all stellar bodies into one point, super-heating them and causing what could be considered an inverse of the Big Bang.
It truly is interesting to see how accidental and yet how acuminous it is. And hopefully you will be stunned at how much of an accidental and intentional genius Robert Frost was! And as always, leave any likes, comments, and/or questions you deign to do so! And thanks for reading. Hopefully I will see you soon in a new update!
--J
Expansion
Now's the more difficult part, which is understanding what I mean by expansion. I will have to explain this better in another post as there are other important concepts to define but I will explain how this relates to the poem at least. When we normally say expansion, we mean things are moving away from each other in space. This would imply that all objects in the universe move away from each other in a fixed space. Strangely this is not true because it is not under this concept of expansion. Rather, it is not the bodies expanding in a fixed space, but fixed bodies in an expanding space! This is a strange concept to absorb, because it is hard to imagine that the bodies are moving, but not moving. It sounds like some really badly-worded Star Wars quote, but let's make it easier shall we? Imagine that you have a balloon, and you draw two dots on it with a marker maybe an inch apart. Now you blow up the balloon. The dots have not physically moved on the balloon, have they? No of course not! But you must admit that upon visual inspection they are definitely further apart from each other. That is because the actual space that the dots are in has expanded, which pushes them away from away from each other. If you replace the dots with two stars and the balloon with the universe, that is something close to what I am trying to explain. The universe itself is expanding, but the stars themselves are not actually moving away from each other (to get a little more technical, it is the dark matter and energy in the universe that expands in a very strange way that we don't entirely understand).
So what's the point of all this? Well let's take a look at the poem mentioned in the beginning of this post! When the universe expands, it also cools down (not as much radiation reaches the surfaces of planets, etc.). So when Robert Frost mentions the world ending in ice, it actually is somewhat apt to one way that the world (and the universe) is hypothesized to end, which is that the universe will expand so greatly that it will cool beyond the point that is sustainable for everything. So it seems that Robert Frost was not only a celebrated poet but also an unknown and unintentional physicist! The other concept of ending in fire is also apt, as there is another theory that the expansion of the universe will soon slow down to the point where the intra-galactic gravitational forces will pull all stellar bodies into one point, super-heating them and causing what could be considered an inverse of the Big Bang.
It truly is interesting to see how accidental and yet how acuminous it is. And hopefully you will be stunned at how much of an accidental and intentional genius Robert Frost was! And as always, leave any likes, comments, and/or questions you deign to do so! And thanks for reading. Hopefully I will see you soon in a new update!
--J
