Rongqing Dai Abstract This short essay proposes the conceptual separation of the notion of universe from the notion of space as already implied in my pervious works, which is unprecedented in physics by and large due to the fact that the notion of universe came to life with the undertone of filling the whole space. Nevertheless, the evolution of human civilization has come to such a point that we have sufficient reasons to conceptually separate those two notions. This separation could help us to have a better cosmological understanding of the universe, as well as space and time. Keywords: Universe, Space, Time, Big Bang, Cosmic Expansion 1. Background Ever since humans developed the concept of the universe, the basic imagination of the relationship between the universe and space has been that "the universe fills the entire space". Under this premise, a very natural inference is that "there is nothing outside the universe", and thus "the universe has no outside". When the theory of the expansion of the universe and the Big Bang was proposed, the concept that the entirety of space is the entirety of the universe (i.e. the space it occupies) was naturally carried forward. Not only that, but on this basis, people very naturally equated the expansion of the universe with the expansion of space, and further combined it with the special theory of relativity to draw the conclusion that "spacetime was created in the Big Bang". The most famous promoter of this theory should be the late Stephen Hawking. In the 21st century, the notion that "the universe fills the entire space" and that "spacetime originated in the Big Bang and has been expanding ever since" have become a deeply rooted fundamental understanding of the universe and space within the academic community. As a result, more than a hundred years after the theory of cosmic expansion was proposed, this concept was actually used by some staunch opponents of the Big Bang theory as a reason to oppose the theory of cosmic expansion (it should be noted that the Big Bang theory is based on the theory of cosmic expansion. Therefore, one of the most common ways to deny the Big Bang is to deny the theory of the expanding universe). Obviously, this is not merely a physics problem but rather a philosophical one. In fact, it is precisely the concept of the Big Bang that can help us break away from the long-held notion that the universe fills the entire space. As mentioned earlier, the Big Bang theory originated from the theory of cosmic expansion, and the main empirical basis for the theory of cosmic expansion is the redshift phenomenon observed by Hubble around one century ago. It is particularly important to note that the redshift phenomenon can only serve as an empirical basis for cosmic expansion and does not indicate that space is expanding along with the universe. This realization naturally reminds us that the Big Bang theory, which is directly derived from the theory of cosmic expansion, can only imply that the universe was created in the Big Bang, rather than space or the so-called spacetime was created in the Big Bang. When we separate the concept of the universe from that of space, it becomes much easier for us to accept the conclusion that the universe created by the Big Bang is expanding in an infinitely large static space, a conclusion that can be directly drawn from the phenomenon of cosmic redshift. 2. A little historical speculation It could be reasonably assumed that the most primitive perception of space by human beings is that they live in an endless vast space. Then, when the concept of the universe emerged, the universe was basically regarded as the space containing all things, that is, the universe is space. After the discovery of the redshift phenomenon in the universe, it was concluded that the cosmic redshift was caused by the mutual distancing of stars, thus leading to the hypothesis of the expansion of the universe. But if it is constantly expanding, it is quite natural to think that the entire universe expanded from a point of extremely high density, and thus the Big Bang theory was born. However, because the concept of the universe was basically equivalent to space from the very beginning, particularly because of the popularity of the special theory of relativity in the physics community during the same time period of the emergence of the theory of cosmic expansion, which claimed that time and space could be interchanged, the idea that the Big Bang produced spacetime emerged. On the other hand, the concept that the universe could have originally been a very small point provides the possibility of separating the universe from space: since redshift only indicates that stars are moving away from each other, the conclusion of space expansion drawn from it is an unnatural leap. As long as we return to the ancient concept that space is static and infinitely large, we can allow the universe to freely expand within space starting from a point. 3. Some relevant precursory works of mine On the other hand, in the past few years I have not only refuted the theory of special relativity that integrates time and space through motion into the so-called spacetime, but also criticized various theories about the change of the speed of time in articles and online discussions and clearly pointed out that at least so far we have no reason to believe that the speed of time can change as claimed by the theory of relativity [[1]]. Not only that, I have also criticized from several different angles the claim of general relativity that gravity is caused by the curvature of spacetime, and pointed out that at least so far we have no reason to believe that the size of space can change under the influence of gravity as claimed by the theory of relativity [[2]]. But in the meantime, I have also repeatedly expressed my opinion in different occasions that Big Bang as a philosophical notion for the creation of the universe is plausible [[3],[4],[5]]. That is to say, over the past few years, on the one hand, I have supported the concept that the Big Bang gave rise to the universe; while on the other hand, I have opposed the idea that space and time were created by the Big Bang. Obviously, a direct entailment of my stance is to separate the concept of the universe from that of space (of course, from time too). 4. Final Remarks Although implied in my previous works, the conceptual separation of universe from space is first explicitly proposed in this short essay, which is not only unprecedented in my own works, but also unprecedented in physics by and large due to the fact that the notion of universe came to life with the undertone of filling the whole space. This happens because the evolution of human civilization has come to such a point that we have sufficient reasons to conceptually separate those two notions as discussed in this short essay. This separation could help us to have a better cosmological understanding of the universe, as well as space and time. References
[[1]] Dai, R. (2022). What is Time? Retrieved from: https://www.academia.edu/94026042/What_Is_Time [[2]] Dai, R. (2024). What Is Wrong and Right with General Relativity? Retrieved from: https://www.academia.edu/120069979/What_Is_Wrong_and_Right_with_General_Relativity? [[3]] Dai, R. (2025) What is Right and Wrong with Big Bang? Retrieved from: https://www.academia.edu/145136764/What_is_Right_and_Wrong_with_Big_Bang [[4]] Dai, R. (2024). When Philosophy is Disparaged. Scholars’ Press. Chp 15 Anti-Big-Bang Confusion, p52. ISBN: 978-620-6-77202-6. [[5]] Dai, R. (2023). What Has JWST Proved Wrong? Retrieved from: https://www.academia.edu/97886597/What_Has_JWST_Proved_Wrong
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