If you rewind the universe back 14,7 billion years, all matter were in one spot, and then started expanding. Do we know where this is in reference to our own solar system? And is there anything there? Or are all matter in the universe just blown inn all different directions and none is left at the "original" spot where it originated
You're envisioning the Big Bang as a cosmological "explosion" in space where the universe is the resulting material expanding in outward all directions.
The problem is, the universe doesn't work like that.
The universe isn't a region of space that is expanding outward into another thing where you can (even hypothetically) fly out to the border and say, "Yup, that's about all there is. Let's use these borders to find the center of this expanding sphere."
The Universe is literally everything there is: space, time, and everything it contains and ever will contain. And the word contains is even a bit of a misnomer in that it suggests a container with boundaries. But the universe is simultaneously both unbounded and finite at the same time. "Finite" refers to the fixed amount of stuff this universe contains (matter, energy, etc)… and infinite because this thing we know as "the universe" has no borders in a sense that we point to or even experience. So how would you even define a "center"? There isn't one.
There's a famous way to help visualize an expanding universe that is both finite and unbounded without a center or borders; it's called "The Balloon Analogy." Imagine our friends in Flatland living in two-dimensional space… where everything they know (their entire universe) exists on the surface of a balloon. If you start to inflate that balloon (the expanding universe), all the little astronomers on the surface will observe that all the surrounding galaxies are moving away from them — and the farther away those galaxies are, the faster they seem to be moving away.
That's pretty much what most cosmologists believe is happening to us.
Going back to that balloon analogy, picture yourself existing on the surface of that balloon-universe and ask these questions again — In my expanding universe (the surface of the balloon), where is it's center? Everything is expanding outward in all directions, so if we rewind back in time, certainly everything should converge somewhere, right? Can we just find the borders of this outward expansion and calculate the exact center? So basdically… "Do we know the exact spot where big bang took place?"
Be careful taking the balloon analogy too far, because it starts to break down in many ways. But the answer to where the expansion of the universe emanates from really is that it emanates from everywhere; everything we know is contained within the origin of our own existence, and there is no center and there are no borders by any definition of existence that we can experience.
As has already been mentioned, the big bang happened everywhere due to the fact that all of time and space was in the same spot at the point of the Big Bang. And so the big bang happened here, there and everywhere. This is also similar to saying that the universe has no centre.
I have seen this phenomenon explained using two pieces of clear plastic marked with the same pattern of dots, except that one has been scaled up (i.e. to represent an expanded universe). If any pair of corresponding points is selected, than it appears as though the selected point is at the centre of the universe because all other points have become further away. Points that were of equal distance from the selected points will be the same distance as each other from the selected point. This works for any corresponding pair of points.
My understanding is that the Big Bang took place everywhere. That "one spot" expanded into the Universe as we see it now. There is no distinguished spot within the current Universe corresponding to the Big Bang.
It's all around us.
The way I explain it is that we are in the centre of the universe (I don't mean in the geocentric way as thought back in the middle ages where all is moving around us). Everywhere we look we see the past: our Sun how it was 8 minutes ago; the closer star, Alpha Centauri, as it was 4.2 years ago, the Andromeda galaxy's light took 2.5 million years to reach us, and further on we go... but as you can imagine the universe goes in all the directions...so there's not a single point in space but in time.
Hope this drawing helps to understand it, Earth is in the centre, the Sun could be at certain radius and each object in our universe will be placed somewhere between us and the beginning of the universe: the big bang at 13.77 ± 0.059 billion years ago
Having this in mind you can then understand why we see the cosmic background radiation coming from all the directions.
I have pondered this issue for nearly 35 years. If the universe came into being by way of a Big Bang process we will probably never find the exact center at which it commenced:
REASONS BB CENTER MAY NEVER BE FOUND
1. We should always keep this in mind as our starting point: We did not see the beginning of our universe take place. There are no eyewitnesses who can tell us what actually happened. Therefore, it is a 13.7+ billions of years old COLD case. In other words everything we put forward regarding the beginning of the universe will always be only speculation.
We have no way to prove anything that we hypothesize regarding how our universe commenced (no matter how many theories are proposed regarding the beginning of the universe nor how good they and their corresponding math equations appear to be, there is no way to fully test them to prove out anything they make claims for).
In other words, even if the numbers do not add up perfectly you can always come up with another constant or sub-theory that makes it look more correct, none of which is provable in our real world predicament. This means it may be impossible to determine if the BB took place or if a center ever existed at all.
2. That said, even if the Big Bang is responsible for how the universe expanded to its current state, problems or barriers may prevent us from locating the exact location of the center from which it all started.
3. The starting point, regarding the BB, was supposedly a state of singularity. What singularity actually would be is not really known. However, its state would be a point about the size of a marble in which presumably all the laws of physics as we know them are broken down, a kind of state of total annihilation of all atomic structure and its various particles. If the supposed early "super" inflation phase occurred it would be opaque because photons would not be present nor released during this phase. Therefore, our view of events up to this point would be obscured.
In other words, we can never see through this phase nor would there be any way to see this phase of inflation because we would need to see photons. Only where photons are released are we able to see even part of what was there (the so-called visible universe limit).
4. Because we can not see beyond the visible universe (which would include the parts of the electromagnetic spectrum that can not be seen by the naked eye, that can only be seen through equipment that can detect invisible wavelengths) we would have almost no chance of ever finding the exact center of the BB.
5. According to one theory space exists and inflates separate from matter and energy. That is we are located within and are a part of this inflation. According to this proposal space (fabric of spacetime) is inflating in all directions all around us, that we are within the spot. The result being that we can not detect a direction in which the BB started from. Supposedly, because we are located within the BB inflation, this precludes us from having a frame of reference that would allow us to have the ability to trace back and locate the exact center or even the general location of the BB starting point.
6. The real world frame of reference for our universe is three dimensional plus time. The visible universe matter is not uniform in all directions. That is all the galaxies, etc. are not uniformly spaced along its x, y & z axis (unlike the two dimensional demonstration models with evenly spaced matter). Since, supposedly the Big Bang started with a very tiny singularity blob (at least for this theory), smaller than a marble, then there ought to be various vector trails (even if they are fragmented or somewhat askew, blurred or dissipated) of some sort going back to the marble size singularity state or at least into the outward edge area of the 'super' iflation phase (especially since matter is not uniformly spaced and would have to change direction and consistancy in order for large areas or gaps at irregular intervals to be present now). However, so far we have not been able to locate any evidence that would suggest that the BB came from a particular direction which has also precluded us from locating a BB center.
7. Unfortunately, two dimensional demonstation models lack ability to show true three dimensional effect regarding starting at a tiny point through the present state of inflation or expansion of 13.7 billion light years. In other words, if we look across through our universe sphere (matter does not exist evenly spaced on two dimensional planes here) somewhere at least near part of the edge of our visible universe we should see at least some large area where galaxies are much closer together compared to say an eight or ten billion light years area around where our galaxy is located now. So far we have not found any evidence. Perhaps this means the BB did not occur.
Certainly if the universe had a tiny starting point there should be a visible change somewhere in an inflation or expansion that covers such a huge area of more than 13.7 billion light years (there would be some indication in which direction we should concentrate our effort to find something regarding at least the general direction of the BB's original location). So far such indication has not been found.
8. Also, there may be a force(s) outside our universe that is the driving force for the inflation or expansion of our universe, in which case it would most likely make it impossible to ever find evidence of a center if one ever existed.