If I understand the big bang theory correctly our whole universe was in a hot dense state. And then suddenly, rapid expansion happened where everything expanded outwards presumably from the singularity. We know for a fact that the universe is expaning and has been expanding since it began. So, theoretically if we go backwards in time things were closer together. The more further back we go, the more closer together things were. We should eventually reach a point where everything was one, or where everything was none (depending on how you look at it). This point should be the center of the universe since everything expanded from it. But after doing a bit of research I have discovered that there is no center to the universe. Please explain to me how this is possible.
Thank you!
In: Physics
One of the most common ways to describe the universe is the balloon analogy.
Whereby it is depicted that all of the galaxies and stars and matter that make up the universe are on the outside of an ever-expanding balloon.
The common misconception though is that the interior of the balloon represents the volume of the universe and this is not the case.
The surface of the balloon essentially being a 2D service represents 3D space. The ever expanding air volume inside the balloon can represent the fourth dimension of time. So you’re depicting a four dimensional construct with a three-dimensional object.
Tldr; The surface of the balloon is the three dimensional universe and the air volume inside is the fourth dimension of time. The surface of the balloon has no center and if you were an observer on the surface of the balloon every spot on it would look like the center from every other observable point.
Homer J Simpson’s ‘Donut Theory’, now with science https://www.space.com/universe-might-be-shaped-like-doughnut-not-pancake
I find the balloon metaphor, though flawed and incomplete, helps with wrapping our 3D heads around the issue of the center. If you take a balloon and inflate it the surface area grows in all directions. Any 2 spots on the surface will grow away from each other. If you were a 2 dimensional being living on the surface you would see everything moving away from you regardless of where you stood. From the point of view of a 2D being there is no center to the surface of the balloon because the center exists in the 3rd dimension. We are in a 3 dimensional state of expansion the supposed center is not.
The ‘nothingness’ at the center could just be unpercievable to us, as its furthur ‘along’ the Big Bang than us.
Take a sheet of paper. It’s easy to find the middle. Now take that same sheet and form it into a perfect sphere. Now where on the surface of that sheet of paper is the center? Everywhere…. and nowhere.
This is not to imply that the universe is, or is not a sphere, but simply to illustrate that it’s possible to have a shape where our idea of the middle doesn’t exactly make sense. At best, it shifts from the surface of the sheet of paper, to an imaginary point at the ‘core’. That was just shifting from 2d to 3d. We don’t even really know how many dimensions the universe has. Heck, we don’t even know the shape since we can’t step outside and look at it as a whole.
You may have the picture in your head of a little squashed universe as a point, that big bangs, and expands outwards? But… Into what? Everything that is the observablr universe, including the space between things, was in that point. There (likely) is no outside we can decipher from inside. So that tiny point is infinite (likely, or perhaps finite without a border) and so has its own positional center of sorts, but the whole thing expanded from there, but it itself is not the center of something, it itself *is* in fact everything. I think you’re stuck on the visual of a point in 3d space ballooning from the persp8of an outside observer. It’s not quite like that, put yourself inside the point, remembering it is infinite but also infinitely condensed, and reimagine the expansion.
Imagine the universe is on the surface of a balloon. Add a dot to any place on the balloon. That dot is you.
Any direction you head is continuous without any sort of end to it. You will eventually loop back to where you started but that starting point is just a random point on that surface.
Because there are no defined boundaries, there is no center (there is no start or end either).
You can inflate the balloon which will increase the distance between your dot and any other point on the balloon, but the surface remains continuous and without any boundary or any center.
That’s the simplest explanation I can give without getting into a poor explanation of things like space manifolds. 🙂
Someone once asked this in a Physics III course I took in college and I loved the professor’s response:
>The line of the equator is defined via a metric: the mid-distance between both North and South poles.
>The poles are defined by physical circumstance: they’re the two spots on the Earth where it’s rotational motion does not cause angular displacement.
>The Prime Meridian is defined by coincidence: It’s the line that passes through both poles and an observatory located in Greenwich, UK. That town could have been placed anywhere. Nobility argued it should run through London, Paris, and other locations instead of where it is today.
>Null Island (0N, 0E) is a buoy that was installed where the Prime Meridian and Equator intersect. Most terestrial navigation measurements use this as the origin, the “center of the map” if you will. And yet, it is still coincidentally located way off the coast of Africa because of the arbitrary definition of the Prime Meridian.
>Suppose an alien craft parks 10 light minutes above the planetary plane (the imaginary disk that all the planets seem to be locked to). Where do you think they’ll decide to put the “center of the map”? Should their algorithms for navigation be sensitive should they pick a different location? Of course not.
>There are two possibilities: (1) The universe is finite. In that case, we can also prove that it needs to loop around itself much like the surface of a sphere, like the surface of the Earth. or (2) The universe is infinite. In that case putting “the center” anywhere doesn’t matter because we’re just measuring things *relative* to whatever arbitrary origin we use, just like in Case 1. Either way, we have a “centerless” metric space.
QEDMF
Think of the surface of a sphere. Where is the center?
What are the chances that we’re only as smart ants on the scale of the universe, and what we “calculate” the universe to be, is only a tiny piece of something completely different? What if we’re just bacteria under a microscope, and what we think is the edge of the universe, is just the edge of a drop of liquid that we reside in?
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