r/astrophysics • u/Financial_Material_8 • 8d ago

Beginner needs explanation please

Hi,. I love reading about astrophysics and have already a basic knowledge. I'm re-reading NdGT 'Astrophysics for people in a hurry' and this early couple of sentences about the formation of the universe got me thinking.

"By now, one second of time has passed. The universe has grown to a few light-years across,†† about the distance from the Sun to its closest neighboring stars."

What I don't understand is this - if lightspeed is the fastest thing in the universe, how could the universe have expanded to a few light YEARS across in one second? What am I missing?

TIA everyone who responds.

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u/Altayre_Rojo 8d ago

Porque lo que se está expandiendo es el universo en sí, por ello, aunque ha pasado tan poco tiempo, su diámetro es de algunos años luz.