A potential answer to the horizon problem. Further insights into the big bang, the inflation epoch, and the flatness problem.
As the title says, in this post which will most likely be QUITE extensive and dense, I will attempt to tackle and provide further insight into a few fundamental, and bleeding edge theories of our current understanding of physics, and the universe. I will also rely heavily on bold / bold and italics font in this post, and whenever I do that, it’s either an incredibly important core point, or also one of my proposals after the “PROPOSALS” part of this post and onwards, or if it has an underline and is both in bold and italics, then it’s a link either to a previous blog post of mine, or a news article.
So, first scientific blog post in over a month, and a proposal one for even longer than that. And the first of either that I will be writing while on my ADD medication, hopefully it’ll help me with this. Christ this will be either very fun, or incredibly frustrating and difficult. Let’s see if during this blog post, I end up finding out that the total volume of the inside of my skull is either incredibly large, or INCREDIBLY small. Before we get into the nitty gritty, my proposals, and everything else though, we should probably first discuss what the horizon problem is, the inflation epoch, and my briefly discussed in previous blog posts big bang and flatness problems.
To start with the horizon problem. What is it? Well, the horizon problem aka. the homogeneity problem, is a cosmological puzzle that arises from the observation that different regions of the universe, even ones that are many many millions or billions of light years apart, appear to share almost identical properties with each other, such as temperature, FLATNESS / uniformity / isotropy, and a few more, even though they appear to be too far apart to have ever been in any contact with each other. And because of that, it’s not immediately clear as to how exactly these sections could have “Communicated” with each other, or learned to assume almost identical states via any other method.
To address the temperature part first. Basically, scientists from various observations have realized how cosmos, everywhere, seems to be at a very uniform and stable temperature of 2.7 kelvin, again no matter the distance. The standard and classic big bang model cannot explain this problem either, because it suggests that these regions of the universe would not have had enough time to exchange information or energy, to become this homogenous further on and remain that way, essentially because they would have literally exploded far apart from each other in an instant, hence “Big bang”. This is where the theory of INFLATION comes in.
Insight into inflation: The theory of inflation proposes that right after the big bang, the universe underwent what is called an “Inflationary epoch”, one of many incredibly important epochs and “Episodes” of the early universe that was responsible for shaping and molding the universe into what it is today, giving birth to all of the fundamental laws of physics, forces, and quantum mechanics that we know today, etc. The inflationary epoch is believed to have lasted from 10^-36 seconds to between 10^-33 and 10^-32 seconds. So basically, to try to give some context as to how insanely brief that time period is and go on a brief tangent, you might have heard scientists referring to such large numbers by repeating the word “Billion” or “Million” or whatever multiple times, and here’s how that works. Basically, 10^36 is a 1 with 36 zeroes after it, so 1,000,000,000,000,000,000,000,000,000,000,000,000, and to avoid diving into the quite confusing world of number naming schemes beyond “Billion”, in layman’s terms you could also say it as “One billion billion billion billion”, with each billion being 9 zeroes as you already know, and multiplying that by the 4 times you say “Billion”, you get 36 zeroes. In the case of 10^-36, because of the minus before the 36, you would move the decimal place to the left, instead of right, so you would be diving well below 0, instead of above it. So in this case you would get 0.000000000000000000000000000000000001, if you remove the “1”, and the decimal place . you see that you have 36 zeroes again, but running to the left from the “1” instead of right as previously. And in this case in layman’s terms, you’d refer to this as “One billion billion billion billionths” of a second, that is FREAKING TINY, and to get the other estimations of 10^-33 or 10^-32 you simply remove three or 4 zeroes from that number respectively. Either way, it’s insanely tiny. End of insight.
To try to at least provide SOME distance of context towards how tiny that period of time is, a single proton is about 0.84 femtometers, with 1 femtometer being one quadrillionth of a meter (One billion millionth of a meter). And as you might also know, the speed of light is the fastest possible speed anything can physically move in this universe, being about 299,792 kilometers PER SECOND, enough to circle the earth around the equator about 7.5 times in one second. So how fast would it take for light to travel that insanely tiny distance, from one end of the proton to the other? Well, that would be about 2.8019 x 10^-24 seconds. In decimal form that would be 0.0000000000000000000000028019 seconds.. which is still an INCREDIBLY fast and tiny amount of time still, but compared to the previous 10^-36, scientifically speaking it’s about 12 orders of magnitude (12 decimal points / zeroes) faster, or in more layman’s terms, a TRILLION times faster (trillion comes after billion). To try to give you some more context, let’s briefly discuss how small the nucleus of an atom is compared to its entirety, the place where the protons and neutrons are. About 99.9999999999996% of atoms is empty space believe it or not, and if you were to to take say a hydrogen atom with 1 proton and 1 electron, and blow it all the way up to the size of a giant foot / soccer ball stadium, then the electron would be spinning around on the outside of that stadium, and the proton / nucleus of the atom would be the size of a tiny blueberry in the middle of the stadium, everything else is just empty space. Or if you were to take that blueberry and blow it up to the size of the earth, then the electron would roughly be orbiting around the distance of the moon, I will embed a picture that shows the distance between the earth and moon, roughly to scale with their respective sizes too.
The distance between the earth and the moon is about 384,400 kilometers on average.
Even sitting here myself currently trying to imagine all of these scales, and writing these past 2 paragraphs out and trying to explain it all away, I am having quite a headache haha. Anyway, I think that explains inflation, let’s move on to flatness. Right, flatness, what the hell was I going to say about it even, and what does this have anything to do with the Horizon problem, or how will I tie it into this? They are incredibly similar, and closely related yes, but still two different problems. The flatness problems focuses entirely on the concept of the universe being scarily flat regarding its EXPANSE, when according to our mathematics and theories, it SHOULDN’T be. Whereas the horizon problem focuses ENTIRELY on the UNIFORMITY of TEMPERATURE in the whole universe, that being the previously mentioned 2.7 kelvin, and why that is the case, assuming that the inflationary epoch never existed, which again as stated previously, is the currently proposed solution as to how the universe, even in its early years, was very uniform and smooth when it came to both temperature AND expanse, which as also stated before, continues to this very day. So the two problems can be extrapolated back to the same proposal, inflation, but yet are a bit different from each other now. In that case, I would say that it’s quite silly to split the two problems into two separate things when obviously they are just two parts of one bigger problem, so I would propose tying them together into what I would call “The Uniformity Problem”.
Insight into the flatness problem: But yeah, that tangent aside, flatness. I previously discussed this here , but to summarize: Universe very big, very flat, scary, scary is bad. We no want scary. We no want the Greek letter omega Ω which we use to represent the flatness of the universe, to be exactly 1. We either want Ω to be less than 1, or bigger than 1. If it was less than 1, then the universe would have negative curvature, it would still expand out into infinity, but at least it would have a discernable shape, and that could still be incredibly vital knowledge for us in the understanding of everything regarding the universe, either way if it was equal to 1, or less than 1, it would result in a pretty depressing “heat death” of the universe. Conversely, if Ω was bigger than 1, then the universe would not be infinite, but would be spherical in shape, however, expansion would eventually stop and reverse, leading to the universe essentially walking backwards in time and its own age again, becoming incredibly hot, dense, energetic, until it got to a point just as small as it was at its birth and big bang, also known as “the big crunch”, it would also not be a nice way to go, but at least it would save us from the endless amount of existential crisis regarding how something infinite could come from nothing essentially, or something that was so incomprehensibly small. End of insight.
Right so, to go back to addressing that 2.7 kelvin temperature thing and its uniformity. If that figure at all sounded familiar to you, then you might realize that 2.7 kelvin is the exact same temperature that the cosmic microwave background radiation (Picture below) currently is. So case closed on the horizon problem right? Why is the temperature of the cosmos 2.7 kelvin, well because just like the cosmic microwave background, that’s exactly what it is, the afterglow of the birth of our universe, the big bang! However, unfortunately it’s not that simple, as demonstrated before, scientists are bad at categorizing and naming things, and the horizon problem SPECIFICALLY wants to know why the temperature of the universe was so homogenous and smooth IN ITS EARLY YEARS as well, cutting out the inflation proposal.
The 2nd out of the three renditions of the picture of our universe in its baby years, specifically around 380,000 years after the big bang. The fluctuation of temperature between the blue spots, and the red spots is only a few thousandths of a kelvin, 2.721 - 2.729 kelvin specifically. INCREDIBLY uniform and isotropic despite its looks.
So, without inflation at all, solving the horizon problem becomes a lot more tricky, but that doesn’t mean that there’s no room for theories or explanation to occur still, which is exactly what I’d like to do in this post, and also as a byproduct, potentially provide more insight into the big bang, the flatness problem, and the previously talked about inflationary epoch. So let us get into the proposals.
PROPOSALS:
To Include Inflation:
If we were to include inflation, and had to answer why the universe was, and still is very flat and uniform. As mentioned previously, the proposed inflationary epoch is meant to be a solution to that, namely that before the big bang and its rapid expansion, there was an INCREDIBLY brief pause between that, and when inflation kicked in, which is proposed to have been just enough time for the early universe to somewhat equalize in temperature and energy, which is still reflected today, however not so much to the point where complex structures couldn’t form, or other forms of matter like dark matter, which on that note, is also incredibly pivotal for the formation of our universe, and the birth of stars, planets, galaxies, etc. It is also responsible for most of the energy / force required to hold galaxies together. And it was theorized that in the incredibly early universe, dark matter liked to assume shapes representing webs and filaments, which is also reflected still today, the “Cosmic web”. And because of that, matter got pulled into, and along said webs and filaments, until enough of it gathered to start condensing and fusing into the first structures like stars. And the 2.7 kelvin that our space is at currently, could be the potential left over energy that did not get captured by all the pockets of condensed matter and dark matter, think of it as the “Afterglow” of the big bang, which is exactly what it is as well, in the form of the cosmic microwave background. And whatever roughness there was, was stretched out into insanely massive scales by said inflation, to the point where they appear to be smooth now. Think of it as trying to see the roundness of the earth while standing at surface level, quite hard.
Another potential explanation to the uniformity of the universe, is the quantum foam / vacuum theory. Namely that just before the big bang and subsequent inflation, the entire universe was nothing but an incomprehensibly small point of bubbling quantum fluctuations, which then got stretched into large scales with the big bang and subsequent inflation. Acting as seeds for the formation of the larger structures in the universe that we can currently see and observe.
Empty space isn’t truly empty. There are all of these quantum fluctuations of energy taking place everywhere and INCREDIBLY quickly. The framerate of this simulation is One Million Billion Billion frames (Pictures) per second, and the section of space is so small you can roughly fit two protons in there.
Insight into the big bang: How can something come from nothing? If you really dive into our early universe and what was taking place, and I mean like trillionths and billionths of a second after the big bang, and all those eras and epochs, you'll realize that even for an intelligent person it's basically impossible to wrap your brain around the insane and sheer freaking scale of temperatures, densities, energies, and everything else that was taking place. And to hammer that point home, the amount of energy and heat from back then, in such an incomprehensibly small and dense scale, was so incredibly large, that 14 billion years later it was enough to give us almost 100 billion light years of observable cosmos absolutely overwhelming with galaxies, stars, planets, and whatever else (And to digress, that's just merely FIVE percent of the total matter of our universe), and whatever else lies beyond the observable boundary. So again, it's not unreasonable to think that the universe just before inflation and the big bang might've been just a soup of quantum fluctuations, which then got stretched into such insane scales. End of insight.
Scientists very recently discovered the INCREDIBLY low frequency hum of supermassive black holes in the form of gravitational waves, and discussed that the big bang itself might have also left over residual gravitational waves, which they wanted to figure out how to observe, exactly like the "gravitational wave background" of the universe, and said that the wavelengths of said gravitational waves would literally be as wide as the observable universe itself, so again, incredibly smooth and homogenous. But yeah, we already know that due to dark matter, the incredibly early universe already started to take a "Web" and "Filament" shape, which continues to this very day, so again, what if that 2.7 kelvin is just the remaining energy and afterglow of the big bang that did not manage to get caught in any of those dense regions of dark matter, and those matter webs and filaments, and was instead left wandering around between the space that is between these dense clusters of dark and regular matter?
To demonstrate my theory of the 2.7 kelvin being the residual energy, temperature, and afterglow of the big bang, you can just take a piece of metal and heat it until it's bright red hot and white, and then leave it to cool down by itself, yes it might not take long at all for it to cool back below the draper point (The point where any solid material starts to visibly glow from heat), but it's still going to remain warm for quite a long time afterwards, because the more it cools down, the slower it's going to keep cooling down. Especially when the environment around it is also pretty warm.
To cut out inflation and directly approach the horizon problem, which is also my main focus with this post:
We can start with just one word. Balance. We already know that physics, and subsequently, our universe, tends down toward the path of least resistance, the least energy consumed, the most efficient, and towards balance, where the energy consumed and the energy let out become equal and balanced. Refer to entropy, the observation that everything in the universe tends towards the state of high entropy, or high randomness, or a state where there is not enough condensed and ordered energy in the universe to achieve anything meaningful anymore, like forming stars or planets or literally anything. And how currently our universe seems to exactly be heading towards a state of high entropy, via heat death, by how its expanding and it seems to be only accelerating.
Even without inflation, it’s an already verified fact that the universe can, and has already gone through many states of different sizes, and subsequent densities and energy states, recently scientists had once again proven Einstein's general relativity correct for the umpteenth time by observing that the very early universe appears to run 5x slower than our current universe. Due to time dilation which is one of the products of the theory of general relativity, namely that relevant to this context, objects of high mass and thus density curve space AND time, and what it ends up doing with time, is that time for both the said massive object, as well as anything around it close enough, will run slower than time for everyone further away, and as a distant observer, you would see that too. And in this case, that was exactly because the universe was DENSER, HOTTER, AND THUS SMALLER in its early years. So again even if inflation was never a thing, the universe ABSOLUTELY has still appeared to have gone through many stages especially in its early years. And again, even without inflation, that would probably still be enough to explain the thermal homogeneity and isotropy, because the OBSERVABLE universe today is almost a massive 100 billion light years across, FILLED with only that FIVE PERCENT of the total matter of the universe, and who knows whatever else that lies beyond.
So, you go back and forth with that, and you'll eventually realize that we still get back to the one and same point, being that the total universe, unobservable universe included seem to be incredibly flat, homogenous, very isotropic, and is STILL EXPANDNG, and only accelerating. You don't need to "Communicate" between yourself and other distant pockets of matter, in order for you all to know what is COMMON SENSE and BASIC LOGIC when it comes to the literal existence of both yourself, and the universe and its rules, and again, those being the laws of thermodynamics, entropy, the seeking of balance and efficiency, and all of the responsible forces like gravity, the weak and strong nuclear forces, and electromagnetism. If the universe had evolved those previously mentioned 4 forces in its incredibly early years, then there’s no need to communicate with anyone in order for you to simply know the rules. You don’t go to a country, and somehow have to either communicate its rules and laws with someone no matter the distance, or you go to jail for breaking them. The rules and laws are already written down and set in stone, all you have to do is know them, and then you’ll just automatically behave accordingly in your best interests.
14 billion years is a ton of time, especially the time between 380,000 and 14 billion. Hell, 380,000 years itself is already a huge amount of time, ESPECIALLY in the world of the quantum, where everything is moving incomprehensibly fast, and constantly approaching the speed of light. It’s not unlikely that everything happening at such insane speeds and high energies, for such a long period of time, would not be enough to sort out most of the inconsistencies of the universe, for everything to become more or less stable? What if those slightly hotter and denser pockets in the cosmic microwave background have nothing to do with inflation, or the homogenous temperature and "horizon problem", but are exactly just pockets of regular baryonic / dark matter, that was busy coming together to form gas clouds, and then eventually stars, planets, black holes, galaxies etc. etc., which by the way, is also one of the many theories that gets thrown around regarding the very slight temperature fluctuations in the cosmic microwave background.
When scientists had observed that the early universe appeared to run 5x slower than today by looking at incredibly distant, and thus very old galaxies, how early exactly is “Early”? Well in this case, the galaxy they observed had formed just over one BILLION years AFTER the big bang. And we are talking about a minuscule 380,000 years part of it. So if the universe was that much hotter and dense to the point of running FIVE times slower, when it was only over a BILLION years old, it’s hard to imagine how much denser it would have been a measly 380,000 years after the big bang, or even before it. Probably SO hot that yes, it would again be evidence towards my argument and supporting analogy of "Maybe the very very early universe was so incredibly dense, hot, and high energy that even without a period of inflation or even a big bang, because of all of the high energy, it managed to cool down and spread its energy out enough to the point where at around 380,000 years after the beginning, it already appeared to be very homogenous".
And I am willing to go one step further. What if it wasn't only dark energy driving the universe's expansion in its early years. But also exactly the incredibly dense, hot, and high energy state? Since there was literally no other way for the early universe to get rid of its excess energy and density other than to start expanding itself. If that was not the case, then the universe as we know it today would not exist most likely, and even almost 14 billion years later it would still be in a comparatively incredibly tiny, hot, and dense form still. Which also subsequently violates all of the laws of conservation of momentum, energy, entropy, etc. but clearly that is not the case. SOMETHING was responsible for driving the universe's expansion, even before dark energy most likely, and what if that exactly was the incredibly high energy state, density, and heat of the early universe itself?
And to support that theory even more, as scientists have observed, the expansion of the universe in its early millions of years was incredibly fast and rapid, however, naturally over time it began to slow down as it cooled due to it becoming bigger, and subsequently less hot, and less dense, and less energetic. However, not that long ago, the expansion of the universe seemed to start accelerating again, which it still continues to do today. What if in that exact period of time is where dark energy took over the expansion of the universe? As up until then it had mostly come to a stand still, exactly because of the previously mentioned reasons.
Observe how in this image, how even just 380,000 years after the big bang, or the cosmic microwave background era, the universe was already about 90% of its current size, and how everything before that expanded rapidly due to inflation. And observe how after the Cosmic Microwave Background era, the universe expansion slowed drastically, and appeared to keep slowing even more as it grew with stars, galaxies, planets etc., using up all of that energy from its earlier days and birth. Balance, efficiency.
So as discussed, without inflation, the universe would have highly likely still expanded, driven either entirely, or almost entirely (and partially by dark energy) by its own incredibly hot, dense, and energetic state, if that were not the case, the universe would likely not exist as it does today, and highly likely remain in one incredibly small, hot, high energy state infinitely, which obviously is not possible in any way shape or form according to literally every law we have regarding thermodynamics, energy, and entropy. Which because of how incredibly dense, hot, and high energy the universe is, 380,000 years of nothing but that would more than likely be enough to have already become very homogenous and stable, THOUGH NOT ENOUGH to yet form any massive clumps of matter like galaxies, stars, planets, gas clouds etc. Exactly that period was only the start of such things beginning to happen, and more complex matter beginning to form. So what if that is the exact reason of the CMB already being very homogenous and uniform? The universe's very high energy and dense, hot state had already rapidly expanded it enough, however, it was still too early for complex matter and structures to form, which could also be contributed to by our telescopes so far simply not being sensitive enough to detect any serious changes, what if we were to make a successor to the Planck telescope that is for example a septillion (1,000,000,000,000,000,000,000,000) times more sensitive and higher resolution, and boom suddenly the early universe becomes INCREDIBLY rough and varied actually, exactly because that telescope could pick out those at-the-time INCREDIBLY tiny pockets of compact and dense matter, which again, were only beginning to form.
It's like complaining that an old person's skin is so wrinkly, when their young, baby self's skin was incredibly smooth, despite the many obvious reasons which are the exact same as in this case. Nevertheless, even in our diagrams of the universe, this is reflected by the CMB already being incredibly large, and everything before that rapidly decreasing in size, only after the CMB, and after matter started clumping together to form more complex structures, is when the expansion of the universe started drastically slowing down GO FIGURE. Until not too long ago, dark energy started taking over again. Imagine that the planets, galaxies, stars, etc. etc. are exactly what make the skin that used to be smooth, wrinkly. Because again, in the smooth skin of the early baby universe, there was obviously no significant clumps or pockets of matter, if any to begin with, and as also stated, DEFINITELY no galaxies, planets, gas clouds, stars, etc.
So in conclusion:
With inflation: The 2.7 kelvin average temperature of space is just left over energy from the birth of our universe and its early years, that did not get converted into either dark matter, dark energy, or regular matter.
Without inflation, the horizon problem: The universe would have still expanded and grown drastically, however, it would have been entirely or almost entirely driven by itself, and the incredibly dense, hot, and high energy state it was in, until that energy ran out, and dark energy took over. And the slight fluctuations in the CMB were just sections of matter and dark matter slowly coming together to form more complex structures, and elements. And in both cases, you don’t need to “Communicate” anything in order to abide by the laws and rules of reality, and want to go towards a state of least energy, and most balance.
Christ almighty this one took an entire day to write, and analyze. I apologize if at any point it got a bit too confusing and dense with information, however with such insanely complex topics like these, some things you simply can’t really break down into simple manners and analogies, so I hope that my other attempts at communication were effective enough. However I might realize something new, or come up with something new once I stop being so tired mentally, so I’ll be sure to update this post with it, if that were to happen. Despite the writing of this post eventually becoming severely irritating because of me becoming tired mentally, and thus being unable to properly keep track of everything and break subjects down into simple terms, though I still feel like this ADD medication before it wore off, made a noticeable difference in making the process of writing easier, and either way it was still quite fun, and it was good to write something over a long pause again.
