Asklemmy

The big bang wasn't inside the universe to push anything. The big bang was the universe.

Think of it like leaves on a puddle. As water(space/dark energy) flows into the puddle. It expands. The leaves don't. They just spread out over the surface of the puddle unless they are bound together with other leaves via surface tension(gravity).

I saw a really good demonstration of this once, but I can't seem to find a video of it.

Basically imagine a rubber tube with 4 balls equal distance apart from each other.

--0--0--0--0--

If you stretch the tube from both ends all of the balls move an equal distance apart.

----0----0----0----0----

There is no one ball that is the center or the starting point. However if you focus on one ball while stretching it will seem like the others are moving away from it. But in reality they are all moving away from each other at the same rate.

A lot of people describe the first moment of the big bang as infinitely small, dense, and hot. These descriptions may approximate that first moment of existence, but they slightly miss the mark because in the very first moment of existence, size, density, and temperature didn't exist. There was nothing to compare anything else against.

Instead, let's visualize that moment as infinitely same. Erase all thoughts of violent explosions happening very quickly and instead just imagine a single point of light. Not big, because size requires multiple things. Not small because it encompasses everything. Just one infinite same.

Now, since it's hard for us to visualize change in an infinite void that is simultaneously nothing and everything, imagine that point of light as a magical tank engine at the front of a never-ending train. And our job as conductors of that train is to get to the caboose at the end.

The train cars could theoretically go in any order, but because we conductors are beings of time who need them to arrive on a schedule, we must visit each car in a precise order. And before we can access a car, we must make it unique by showing it something that has never been seen before.

For the first car, this is easy. We simply show it the tank engine at the front of the train. So, the inside of the first car transforms its interior into a copy of the tank engine it's attached to.

But when we arrive at the second car, things are more complicated. The cars have already seen the tank engine. So, instead, we show the second car the first car. And the second car transforms into a copy of the first car and the tank engine attached to that. And inside the copy of the first car is another copy of the tank engine.

As you can imagine, the further down we get on this train, the more this starts to get out of hand. Copies of copies of copies abound. The magic train is powerful, but as mortal conductors of time, we worry our own powers may have limits. So, to reduce the burden on ourselves, we take some shortcuts. Instead of trying to visualize increasingly long nested copies of trains inside each new car we visit, we start to conceptualize these copies as amounts, or amplitudes. When we open the door to a new car, all of the amplitudes inside resonate and interact, becoming maybe more abstract than they are in reality. They form spatial dimensions and physical properties, as mediated by fundamental forces.

These aren't set in stone, but determined by the lens through which we view them. And when we look through specific lenses, we see these forces causing certain repeated amplitudes to intermingle and stabilize to the point that even though all of the train copies are further nested when we step into the next car, we can recognize and identify some of the same structures, just shifted slightly in their spatial relationships since we last witnessed them in the previous car. We call these persistent formations matter. And as their shared spatial relationships cause them to cluster and coalesce, we refer to that as gravity.

While in the early cars, this continuum of space and matter is not impossible to conceptualize, the more cars we travel through, the more apparent it becomes that these increasingly complex objects are becoming more and more isolated from each other. At every scale of amplitude, each nested car is attached to its own tank engine. While these engines can interact with each other virtually, at the end of the day, they are all just virtual copies of the train we are on. It is entirely impossible for any one of these tank engines to travel so far that it reaches the edge of its bounding box. Because that bounding box is just a lens through which we imagine overlapping traits of increasingly many very similar objects. And the more of them we imagine, the more space is required to provide the virtual framework of this lens.

So, when we feel like we are experiencing random events in our small subsection of the universe, those events are not truly random, but instead the result of our precise position in the the universal train we've been virtually sliding through for over 13 billion years. The universe has become so large that it contains every possible event that could have happened in this span of time. The events are not random but calculated, and duplicated every moment so that every time we enter a new train car, two copies of our observable universe exist at a distance so far apart it's impossible to comprehend.

And when we observe celestial objects apparently propelled away from each other at increasing speed, they are not really being pushed or pulled anywhere. It is simply an artifact of trying to keep track of the "same" object in rapidly advancing train cars, while each car doubles in size to contain everything the previous car had, as well as everything new that might emerge from the duplication event. The celestial objects year by year, and indeed ourselves from moment to moment, are never the same thing twice. It's an illusion brought forth by our brains being born into a cosmic flipbook.

Even something as simple as seeing multicolored pixels on this screen is not real, but the result of virtual "tank engines" moving into the same spatial zones occupied by our retinas, which are themselves constructed of virtual trains of varying size. The reason photons move at a set maximum speed which makes them exempt from experiencing time is because they are all just virtual copies of the real locomotive which is driving the whole train. Every photon in our universe is just a make-believe copy of the very first moment of the big bang. A specter of infinite sameness.

So, objects in our universe aren't moving apart as much as the space between them is increasing to account for the overhead of a universe with constantly growing entropy and uniqueness. The extra space represents a boundary which limits how far light can travel and affect matter in its realm of influence. If you're still reading this, somewhere out there, in a part of our universe so far away that light from our known universe will never even remotely reach, there is an opposite you made of antimatter reading the exact same thing as written by an opposite me. But we are only made of matter because of a virtual compression of sameness, so that antiverse may be the exact place where the curvature of the entire universe loops back around and is overlaid upon itself. And the uncertainty of photons may arise from the fact that there are two identical universes overlapped and constantly exchanging probabilities. And this may be the compressive property which allows the fundamental forces to exist in the first place. So, say hi to yourself. You're the reason you're here.

Here's another way to think about the location of the big bang.

If we look at the night sky, between the planets and stars, into the darkness we find there's a faint glow emanating from everywhere. This is the cosmic microwave background, the oldest electromagnetic radiation that has taken the longest possible time to reach us because by this construction you avoided all the other objects in the way. This extends your view of the past to its maximum value: the age of the universe, which is literally all of the available time for photons to travel. Note that this is a simplification because it makes some assumptions about the transparency of the early universe, but it suits us fine.

It's coming from everywhere because all of those places were there at the big bang. Where was the big bang? It was over there. And also in the opposite direction, there. Because all of those places were here.

Try this:

So everything in space, every object had to get to where it is via time. It travelled there. Everything can't be anywhere without time as without time it wouldn't have been able to move there. Time is a constant graph, and as it moves forward, things move around and as such, space is able to exist. This is why we consider space and time to be linked.

Now consider this: if one was to plot a graph of space and time on an x y axis to track an object, there is a point on the graph where time has to be zero, and as such space has to be zero.

This is the big bang.

It is the beginning of the graph. When time was zero, and as such so was space.

Space did not burst out from a single point that we could find out there in space, as there was no point. everything was still everywhere much like it is now, except everywhere just so happened to be so close to one another to be at the same point on the graph. When time began, it just about instantly expanded out, everywhere in every direction. There is no 'center' to this expansion, just like if you blow up a balloon there is no center on the surface of the balloon, it just expands everywhere, and more importantly with time we are able to quantify this.

Think of a balloon. Squish the deflated balloon as where everything was. All of it started at a similar point but then the balloon started expanding and everything is moving away at an accelerated pace from each other

When you look far away, you're looking backwards in time. If you look really far away, you look really far back in time. If you look far enough away, you'll see the big bang.

If you move a thousand light years to your left and do this again, you still see the big bang. Even though your "center" has changed. The big bang is more like a singularity in time than it is in space

No. Local attractive forces, like gravity, especially those at the atomic level, overpower the expansion for tightly coupled systems. So the earth isn't expanding, and neither are the people on it. I don't recall exactly what scale it kicks in at, but there is a good chance it's not even affecting the distance between planets in a system. Most likely it only plays a role in inter-planetary-systems and larger. Ie, stars get further apart from each other.

Edit. This explains it better https://www.astronomy.com/science/does-the-space-inside-an-atom-expand-with-the-universe/

That says that the expansion really only applies to the space between galaxies. In anything smaller than that, gravity still overpowers the expensive forces. Making it far weaker than I initially thought.

I don't know about you but I definitely am. Not sure the big bang is too blame, but I like that excuse.

The forces that hold your body together are many, many orders of magnitude stronger than the acceleration due to the expansion of space.

Check your waistline to find out.

Kind of a tangent at this point, but there is a very good reason that that couldn't be the case: according to the shell theorem , nowhere in the interior of a spherical shell of matter experiences any net gravitational force -- wherever you are inside the sphere, the forces counteract exactly.

Otherwise, though, the metric expansion of space is different from typical movement, and it isn't correct to say that things or being pushed or pulled. Rather, the distance between every pair of points in the universe increases over time, with that rate of increase proportional to the points' distance. Importantly, for very distant points, the distance can increse faster than the speed of light, which would be disallowed by any model which describes the expansion in terms of objects moving in a traditional sense.

You are right that things would still look like we're accelerating away from us, even if we were actually contracting.

Interesting hypothesis! How do we investigate?

What could we expect from a large central gravitational point? We should have other signs of the gravity well:

We would expect a point that we contract towards (and that seems ill fitting, as we see the expansion moves as the observer (including earth) moves), we would expect some kind of mass or similar effect, which would also have a size to fit it in (we know that gravity works different when you're inside the mass, and we would be able to see it, much like black holes or dark matter), we would expect things to orbit the gravity well (which we know that at least our galaxy doesn't orbit us).

You might want to actually check on these things to make sure they apply and are true, but at least at first glance it seems the expansion is better explained without a central gravity.

The Universe probably wouldn't fit in a sphere of any size and it very well may be infinite.

But looking at a very large spherical region like the visible universe from our perspective here on Earth, everything is moving away from us. If objects were being pulled towards one particular edge of our imaginary sphere, it would look very different. We'd see a clear drift in that direction, but it all looks pretty even across every direction we look.

Not unless we were directly in the center of it, in which case everything would seem to move away from us. But even then, if I'm not mistaken, physicists and astronomers have also proven that other objects are also moving away from one another too.

We can tell how something is moving based on the shift of its light, like the Doppler effect. The further something is the more its light is shifted, which was how we came to know this phenomenon in general of increasing size of space between all things.

We are closer to the extinction of the T-Rex than the T-Rex was to the extinction of the stegosaurus.

This more than any other fact illustrates the enormous time span of the dinosaurs' rule.

You do know that only some of the dinosaurs died and one large lineage is still alive, right?

Look at a piece of paper. Mark two points on it that are a good distance apart. Travel can only happen along the surface of the paper. When it's flat, your time of travel depends on the distance between the two points on that paper.

Now dap a spot of glue next to one of the points and fold the paper in such a way that the other point comes to rest close to that glue. Wait for it to bind and then spread the paper a little without breaking the glue. That glued point is a wormhole, a place where two points of that flat 2D universe touch despite not being next to each other. Travel from point A to point B is now a shorter distance thanks to the wormhole. But there is no way in which the paper universe can be described as flat anymore.

Or think of a papermache ball, that's also made from paper but if you travel long enough in one direction, you'll end up where you started. Because it isn't flat.

Now our universe is 3D not 2D, but from a higher dimensional perspective it has the same prooerties of flatness as that 2D paper has for us.

Geometrically speaking, if you draw a really, really big triangle between, say three galaxies, the angles of the triangle add to 180° in a flat universe. In a non-flat space, this would not be the case. For example, if you draw a triangle between, say, New York, Berlin and Rio de Janeiro on the surface of the Earth, the three angles between the lines would add to more than 180° since Earth is topologically a sphere and not flat. And if you draw three lines beween three points on a saddle shape like a Pringles chip, you'll find that the angles add up to less than 180°.

Fun fact: topologically speaking, no matter how you fold or bend a sheet of paper, it remains flat. A cilinder is a flat surface with zero curvature!

What I mean is that what we observe is best approximated as a relative lack of spatial curvature over long distance scales. One of the lines of evidence for this is the cosmic microwave background. A flat topology for space-time over long distances would look different than an open or closed universe: https://phys.org/news/2017-06-universe-flat-topology.html