What Do Seconds Mean During the Big Bang?

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Discussion Overview

The discussion revolves around the meaning of "seconds" in the context of the Big Bang, particularly questioning whether these seconds are equivalent to the seconds defined on Earth and how relativistic effects might influence this measurement. The conversation touches on theoretical aspects of time measurement during the early universe.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the definition of "seconds" during the Big Bang, wondering if they correspond to the seconds defined on Earth and how relativistic effects are considered.
  • Another participant suggests that the time referred to is measured on a clock at rest relative to the Hubble flow.
  • A further contribution explains that there is a distinguished frame of rest in spacetime, which allows for the definition of time since the Big Bang based on the rest frame of the CMB radiation.
  • Some participants express appreciation for the insights shared and relate personal experiences of discovery in understanding these concepts.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and appreciation for the concepts discussed, but there is no clear consensus on the definition of "seconds" during the Big Bang or the implications of relativistic effects.

Contextual Notes

The discussion includes references to specific frames of reference and the nature of time measurement, but does not resolve the complexities or assumptions involved in these definitions.

Who May Find This Useful

Readers interested in cosmology, the nature of time, and the Big Bang theory may find this discussion relevant.

manulal
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I have seen in many books explaining big bang the following kind of expressions..

“In the first few seconds of big bang…”

“In the first few millionth of seconds of big bang..”

Since time is not absolute, what exactly is meant by these “seconds”? Are these seconds same as “our second” – the one defined on the surface of earth.

During big bang, space and matter might be flying in all directions at speeds comparable to that of light (0.5 c, 0.6 c or what ever)

So are these seconds defined by taking relativistic effects into account?

Manulal.
 
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The time referred to is the time measured on a clock that is at rest relative to the Hubble flow.
 
@bcrowell

Thank you very much for the quick reply.

If you don't mind, could you please explain a bit more or suggest a reference?

Manulal.
 
At every point in spacetime there's a distinguished frame of rest, in which the big bang (or its remnants) looks isotropic. Nowadays this frame is the rest frame of the CMB radiation. You can use this frame to define a congruence of timelike curves, which is what bcrowell means by the Hubble flow. The 3-surfaces orthogonal to these curves are surfaces t = constant, and it's this time coordinate which measures the "time since the big bang." (Sorry, that's an awful formal way of stating it!)
 
Thank you Bill. Wasn't that difficult to grasp.
 
Today, I was listening to the third chapter of the audio book “The Hidden Reality Parallel Universes and the Deep Laws of the Cosmos” by Brian Greene in my car.

I was amazed when I heard the author asking the audience this same question. He gave a detailed answer too. This latest work by Mr. Greene is really amazing.
 
manulal said:
Today, I was listening to the third chapter of the audio book “The Hidden Reality Parallel Universes and the Deep Laws of the Cosmos” by Brian Greene in my car.

I was amazed when I heard the author asking the audience this same question. He gave a detailed answer too. This latest work by Mr. Greene is really amazing.

I think that is one of the big draws for me to this kinda stuff. I don't care much for the math of physics, but love the "discovery" or "aha" moments it can cause. Having "confirmation" that your thinking is in the right direction is equally gratifying, no matter how many times it was done before the individual experience is no less significant.
 
nitsuj said:
I think that is one of the big draws for me to this kinda stuff. I don't care much for the math of physics, but love the "discovery" or "aha" moments it can cause. Having "confirmation" that your thinking is in the right direction is equally gratifying, no matter how many times it was done before the individual experience is no less significant.

You are right. Such experiences are so exciting beyond description.
 

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