Based on reading the wiki page of the big bang, a simple question with a probably not a simple answer came to mind.

The statement on the wikipedia page was.

Since Georges Lemaître first noted in 1927 that an expanding universe could be traced back in time to an originating single point, scientists have built on his idea of cosmic expansion.

My question is: Have we measured or found evidence of a detectable origin point of the big bang?


1 Answer 1


There is no single origin point.

Before the big bang, the entire universe was contained in an extremely dense singularity - there was no "space" for the universe to expand into, the very fabric of spacetime was contained entirely in the singularity. There is no single "origin point" in the universe where the big bang took place where we'd see the entire universe receding from us. Rather, from any point in the universe we can see everything else receding. The big bang happened everywhere, since the whole universe, including space itself, came from that singularity.

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    $\begingroup$ The tiny pre-big bang universe was in fact the whole universe? I am not well versed in this topic I'm afraid. $\endgroup$
    – Tom Sol
    Commented May 2, 2019 at 20:22
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    $\begingroup$ Yes, that's the point of the big bang - there was no universe, no space, no time before the big bang. It wasn't a single point of matter sitting in an empty universe, it was just a single point of matter that was the universe. $\endgroup$ Commented May 2, 2019 at 20:24
  • $\begingroup$ @Tom If the universe is infinite, which we believe is very likely, then it's always been infinite, since the dawn of time, 13.8 billion years ago. But in the initial instants of the Big Bang the energy density was extremely high. $\endgroup$
    – PM 2Ring
    Commented May 2, 2019 at 20:54
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    $\begingroup$ @NuclearWang I would avoid any statements containing "single point" altogether. It's very tricky. Once it started to exist it was already infinite. Before that, it did not exist. The boundary conditions are tricky to say the least, and nothing short of quantum gravity would suffice to safely navigate those waters. $\endgroup$ Commented May 2, 2019 at 20:58
  • $\begingroup$ All of the universe that we can see today appears to have been in a very very small region approximately 13.8 billion years ago, That region expanded to the whole observable universe between then and now creating space as it did so. If the universe is infinite then adjacent regions probably also expanded, but we can't see anything that came from them (and never will see it). $\endgroup$ Commented May 2, 2019 at 21:09

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