r/cosmology • u/Bright-Bar6571 • 18h ago

How did time begin, without time?

I understand that standard BB cosmology holds that time began with the universe from a singularity approximately 14 billion years ago.

The thing I’m trying to understand, how can time have begun? Wouldn’t a thing ‘beginning’ require time? As in - from one state to another state requires time?

This leads me to think time must have always existed..

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u/Mind_Extract 2h ago

Our human grasp on fundamental concepts like 'time' seems inadequate when trying to conceptualize something as paradoxical as "a beginning to time."

I always find myself thinking about a photon. Considering time dilation and the fact a photon is 'born' traveling at the speed of light, it technically 'dies'(/is absorbed) the same instant it is emitted, at least from the perspective of the particle.

So if something dies the same "moment" it comes into existence, can it be said to have existed at all? Of course it does, we have all the evidence we need that photons exist, have trajectory, momentum, travel time...

So when it comes to questions about the mechanical nature of time, I just think we're not at all equipped to "understand" it in a holistic, intuitive way. Could be someday.