Posted on 06/12/2025 9:35:23 AM PDT by Red Badger
About a century ago, scientists were struggling to reconcile what seemed a contradiction in Albert Einstein’s theory of general relativity. Published in 1915, and already widely accepted worldwide by physicists and mathematicians, the theory assumed the universe was static – unchanging, unmoving and immutable. In short, Einstein believed the size and shape of the universe today was, more or less, the same size and shape it had always been.
But when astronomers looked into the night sky at faraway galaxies with powerful telescopes, they saw hints the universe was anything but that. These new observations suggested the opposite – that it was, instead, expanding.
Scientists soon realized Einstein’s theory didn’t actually say the universe had to be static; the theory could support an expanding universe as well. Indeed, by using the same mathematical tools provided by Einstein’s theory, scientists created new models that showed the universe was, in fact, dynamic and evolving.
I’ve spent decades trying to understand general relativity, including in my current job as a physics professor teaching courses on the subject. I know wrapping your head around the idea of an ever-expanding universe can feel daunting – and part of the challenge is overriding your natural intuition about how things work. For instance, it’s hard to imagine something as big as the universe not having a center at all, but physics says that’s the reality.
VIDEO AT LINK...........
The Expanding Universe | National Geographic
The universe gets bigger every day.
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The Space Between Galaxies
First, let’s define what’s meant by “expansion.” On Earth, “expanding” means something is getting bigger. And in regard to the universe, that’s true, sort of. Expansion might also mean “everything is getting farther from us,” which is also true with regard to the universe. Point a telescope at distant galaxies and they all do appear to be moving away from us.
What’s more, the farther away they are, the faster they appear to be moving. Those galaxies also seem to be moving away from each other. So it’s more accurate to say that everything in the universe is getting farther away from everything else, all at once.
This idea is subtle but critical. It’s easy to think about the creation of the universe like exploding fireworks: Start with a big bang, and then all the galaxies in the universe fly out in all directions from some central point.
But that analogy isn’t correct. Not only does it falsely imply that the expansion of the universe started from a single spot, which it didn’t, but it also suggests that the galaxies are the things that are moving, which isn’t entirely accurate.
It’s not so much the galaxies that are moving away from each other – it’s the space between galaxies, the fabric of the universe itself, that’s ever-expanding as time goes on. In other words, it’s not really the galaxies themselves that are moving through the universe; it’s more that the universe itself is carrying them farther away as it expands.
A common analogy is to imagine sticking some dots on the surface of a balloon. As you blow air into the balloon, it expands. Because the dots are stuck on the surface of the balloon, they get farther apart. Though they may appear to move, the dots actually stay exactly where you put them, and the distance between them gets bigger simply by virtue of the balloon’s expansion.
It’s the space between the dots that’s growing. NASA/JPL-Caltech, CC BY
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Now think of the dots as galaxies and the balloon as the fabric of the universe, and you begin to get the picture.
Unfortunately, while this analogy is a good start, it doesn’t get the details quite right either.
The 4th Dimension
Important to any analogy is an understanding of its limitations. Some flaws are obvious: A balloon is small enough to fit in your hand – not so the universe. Another flaw is more subtle. The balloon has two parts: its latex surface and its air-filled interior.
These two parts of the balloon are described differently in the language of mathematics. The balloon’s surface is two-dimensional. If you were walking around on it, you could move forward, backward, left, or right, but you couldn’t move up or down without leaving the surface.
Now it might sound like we’re naming four directions here – forward, backward, left and right – but those are just movements along two basic paths: side to side and front to back. That’s what makes the surface two-dimensional – length and width.
The inside of the balloon, on the other hand, is three-dimensional, so you’d be able to move freely in any direction, including up or down – length, width and height.
This is where the confusion lies. The thing we think of as the “center” of the balloon is a point somewhere in its interior, in the air-filled space beneath the surface.
But in this analogy, the universe is more like the latex surface of the balloon. The balloon’s air-filled interior has no counterpart in our universe, so we can’t use that part of the analogy – only the surface matters.
So asking, “Where’s the center of the universe?” is somewhat like asking, “Where’s the center of the balloon’s surface?” There simply isn’t one. You could travel along the surface of the balloon in any direction, for as long as you like, and you’d never once reach a place you could call its center because you’d never actually leave the surface.
In the same way, you could travel in any direction in the universe and would never find its center because, much like the surface of the balloon, it simply doesn’t have one.
Part of the reason this can be so challenging to comprehend is because of the way the universe is described in the language of mathematics. The surface of the balloon has two dimensions, and the balloon’s interior has three, but the universe exists in four dimensions. Because it’s not just about how things move in space, but how they move in time.
Our brains are wired to think about space and time separately. But in the universe, they’re interwoven into a single fabric, called “space-time.” That unification changes the way the universe works relative to what our intuition expects.
And this explanation doesn’t even begin to answer the question of how something can be expanding indefinitely – scientists are still trying to puzzle out what powers this expansion.
So in asking about the center of the universe, we’re confronting the limits of our intuition. The answer we find – everything, expanding everywhere, all at once – is a glimpse of just how strange and beautiful our universe is.
Rob Coyne, Teaching Professor of Physics, University of Rhode Island. He receives funding from the National Aeronautics and Space Administration (NASA) and the US National Science Foundation (NSF).
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Thank you very much and God bless you.
Expanding Ping!......................
It keeps moving. 🎯
My ex-wife thought she was the center of the universe.
It resides within the mind of each and every observer. That’s how I answer ny phone: “Center of the Universe. How may I help you?”
Did she have her own Gravity Well?.........................
Judd Auto in Fredonia, Arizona
;^)
If the universe has no center, which I believe is true, then there is no point from which one could establish absolutely whether events, albeit distant or close, occurred either simultaneously (in the present), or one before (in the past) or after the other (in the future). This obviously affects the flow of time, meaning that from some point in the universe, our past is their present, my father is alive, and my birth is in the future.
I’ve often wondered if “growing” would be a better term than “expanding.” I mean, you have to make room (space) for new galaxies to form, right?
Time is relative to your position.............
My Ex would just Sit Around the House...
And I Mean Sit Around The House!
Then why have astronomers observed galaxies that have crashed into each other and merged?
-PJ
That explanation comports with something I heard about “curved space” a long time ago: if you traveled as far as you could go in the universe, you’d be staring at the back of your own head (of course, that eliminates the time factor but provides some grasp of the concept).
Don’t know where the literal Center of the Universe is, but knowing where the Heart of the Earth is helps understand a parable given by the Creator of the Universe..
I think the word that might fit best is undulating....bulging here....then there....then there...
Yawn...
Anyone who looks can point to a center...
IAC, you cannot tag it...
If you have a good car mechanic, you are lucky.
There is nothing like it
My current mechanic will tell me things like: "this you have to fix now" "this other stuff can wait. "
I often point out that cars are like computers. They work great.....and then, they don't.
I just looooved working on cars in the old days. Timing, dwell, gappers, points, distributors. Once I got used to a car, I could make it purrrrrr.
One sure way to stop a car thief is to remove the distributor cap.
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