Was the expansion after the big bang faster than the speed of light? [duplicate]

I think it's called Planck time and it's the speed at which matter spread during the big bang. Was the big bang expansion faster than the speed of light?

marked as duplicate by ACuriousMind♦, Martin, Qmechanic♦May 31 '15 at 13:47

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• I think you're referring to the Planck Epoch, and not time? – Hritik Narayan May 31 '15 at 12:30
• Yes thats the one sorrry got it wrong – AnonDCX May 31 '15 at 12:31
• – ACuriousMind May 31 '15 at 12:38
• The short answer is yes, space expanded faster than light in the early universe. There are Much longer and better answers by people much smarter than me in the link above. – userLTK May 31 '15 at 12:44

1 Answer

Space still expands faster than the speed of light ($c$) for sufficiently large distances.

Expansion is homologous, meaning that the velocity with which two points recede from each other is proportional to the distance between them. That is, the farther two points are from each other, the faster they recede. In the present-day Universe, two points that are more than roughly 14 billion lightyears apart, move away from each other faster than $c$. In the early Universe, points that were closer receded faster than $c$, and during inflation, points that were closer than the diameter of a (yet non-existing) atomic nuclus receded faster than $c$.

• +1, but I've not heard the word "homologous" before outside biology (wings of birds, pectoral fins of fish and human arms are homologous) or "homology" in algebraic topology. Is its definition exactly what the rest of the sentence implies it is in your field? – WetSavannaAnimal May 31 '15 at 13:36
• @WetSavannaAnimalakaRodVance: Okay, I think the term is not used very often, but yes, you've got it right. I'll expand my answer a bit. Thanks. – pela May 31 '15 at 17:48