Today's question comes again from Dennis who asks,
Where is the physical point of origin for the universe's expansion?Finally, an easy question. Here's your answer: I don't know. And not just me, but science doesn't know either. Well science as we currently know it doesn't know and not only does it not know, but it can't know. How's that for an answer?
Here's what we do know. At some point in time, roughly 13.7 billion years ago, according to Hubble's Law, the universe began expanding. Well, that's not entirely correct. We are able to first observe the universe expanding 13.7 billion years ago. No doubt, something happened prior to that point to create all the matter in the universe and some expansion would have taken place prior to our being able to observe it, however our current scientific theories completely break down in those moments, rendering the point moot. In other words, scientific theory, as we now know it, can only account for what happened after a certain point in the universe's life. Prior to that, we don't know what happened nor can we know.
The point in time in which we can start getting some idea as to what went on is one Planck time after t = 0 for the universe. One Planck time is the length of time it takes a photon to travel one Planck length or 1.6 × 10-35 meters. So, roughly speaking, something happened and at that time and at that place, all the matter and energy in the universe was created and all fundamental theories were combined, living in perfect harmony, no doubt singing joyously about thier grand unification. One Planck time after that, gravity said "Fuck this, I'm outta here" and split off. At that point, theoretical physics can start giving us some idea as to what was going on.
Just as we can't speak to the universe at a time younger than one Planck time, quantum physics says we can't speak of the universe as being smaller than one Planck length as if we did, we'd basically be speaking of a point in space and time that has infinite density, due the fact that everything in creation would have to be packed into one really, really small space. Way smaller than a breadbox.
If you are unsatisfied with this answer and need to know the current center of the universe's expansion, you need only look within. Hubble's Law tells us that the universe is expanding outward equally, such that for any observer it would appear that the universe is expanding outwards from them. Imagine, if you will, that the universe is a cookie and you and I are chocolate chips in said cookie. As the cookie bakes and expands uniformly, you and I will move farther and farther apart. From your point of view, you're not moving at all and I'm the one getting farther away. From where I'm sitting, you're the one moving away. Eventually someone comes and eats us both, that being the inevitable hand of Death, so there's not much of a point in arguing it anyways, but you asked, so I answered.
So there you have it. Where did the universe start? I don't know and neither does anyone else. Well, anyone on this planet anyways. Where is the universe currently expanding from? That would be me. Or maybe it's you. It's all relative.
A special prize will be awarded to the first person to tell me what the title of this post has to do with the post itself. Respond via the comments.
"The Expanding Universe" - Gary Felder, 2000
Wikipedia - Big Bang
Wikipedia - Planck Epoch
Wikipedia - Planck Time
Wikipedia - Graphical Timeline of the Big Bang