The boundless set of concentric spheres
The Big bang theory, as we know it, seems to work beautifully in explaining the present universe and the origin of the observable universe. We tend to use the word observable rather loosely but it does have a subtle importance to it because the universe is very different from the universe we observe, in my opinion. The big bang theory takes us back to the beginning of the observable universe and the age is estimated to be around 13.7 billion years. This estimation comes from the fact that the radiation emitted after the big bang has taken this long to cool to this present temperature that we see.
When we look deep into the sky and look at a star X which is Y light years (distance travelled by light in one year) away, we are looking at the star, Y years ago in the past. This star might not exist now for all we know. When we look at the sun we are looking at the light that was emitted 8 minutes ago. When I look at the screen in front of me, I am looking at it a billionth of a second in the past. Our senses are such that we need a medium to observe and that medium is light. The very innate property of light having a cosmic speed limit restricts us to view the universe only in one direction, the past.
Past, present and future might be coexisting in different frames of references. For instance, my past in space-time can be the future that is yet to be unraveled by an inhabitant in some other part of the universe and the future that we unravel as we travel through the passage of space-time might be overlapping with another inhabitants’ past.
From the scientific findings, we have come to a consensus that the big bang originated from some primeval particle that was extremely dense. This particle exploded giving rise to the universe that we have come to know of. However, it is not clear how this particle came into existence. Some of the greatest minds have suggested that it was due to random quantum fluctuations. If this were the case, taking into account the expansion of the universe, the model in my opinion should be a collection of concentric spheres with the origin as the primeval particle or the big bang. According to this model, the observers are on the surface of the sphere. The sphere that we exist in would be the sphere with a radius of 13.7 billion light years. It would be impossible for someone to travel from one point on one of the concentric spheres to a diametrically opposite point because by the time we get there the sphere would have increased in size.General relativity,however allows that trough wormholes. There also might be spheres that exist beyond the realms of the present sphere and it would also impossible to get to that sphere because we always look into the past as we look farther into the cosmos. Perhaps the sphere is some sort of a cosmic snow globe which allows /gives us the illusion of travelling far and yet never reaching the edge of the so called universe. However we can reach spheres that have smaller radii than ours but inhabitants on the smaller sphere may have no idea that we even exist since we would be beyond the realms of their observable universe. Similarly we might not know about any inhabitants that might exist beyond our sphere. This is why the term observable becomes so important. The universe that might exist beyond the observable universe can never be observed just like the concept of infinity.
Krish Ramkumar
