Time - How Long was the first second?

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In summary: If you're asking "how long was the first second after the Big Bang in terms of our current units of time", the answer is that we don't know, since we don't yet have a complete theory of quantum gravity. The best answer we have is that the Planck time is the smallest meaningful unit of time, so if the universe was smaller than the Planck length at the Planck time, then we can't speak of smaller intervals of time than the Planck time (and if the universe was larger than the Planck length at the Planck time, then the concept of a "first second" is meaningless).
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TonyLondon
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If a singularity slows time. How long was the first second after big bang?
 
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The first second, was by definition, one second long.
 
  • #3
A second by my watch is different from a second next to a singularity. Are you saying it would be the time it took light (if it had existed) to travel 186000 miles (in which case it would have been a really long second)? Just trying to get this concept right in my head before I launch into more study.
 
  • #4
TonyLondon said:
A second by my watch is different from a second next to a singularity.
No, it is not. It looks different to a remote observer but that's a different story.

Are you saying it would be the time it took light (if it had existed) to travel 186000 miles (in which case it would have been a really long second)? Just trying to get this concept right in my head before I launch into more study.
Yes, It would have been the time it took light to travel 186000 miles along a spacetime geodesic, assuming there was nothing to get in its way.
 
  • #5
How do you measure that "first second"?

;)Aleksandr Solzhenitsyn: "Who could act rationally on the first morning of Creation?" (Cancer Ward)o_O

Garth
 
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  • #6
TonyLondon said:
A second by my watch is different from a second next to a singularity.

If you're thinking of a black hole, this applies to an observer "hovering" near the horizon, not the singularity (you can't "hover" near the singularity since you'd be inside the horizon and everything inside the horizon has to fall inward), and, as phinds says, it refers to a second by that observer's clock as seen by a remote observer.

None of this applies to the initial singularity in the Big Bang model. First, that singularity is a past singularity, not a future singularity (like a black hole's); second, you can't "hover" near the Big Bang, since it's really a moment of time, not a place in space (it would be like trying to "hover" near last Tuesday); and third, the concept of "gravitational time dilation" such as occurs near a black hole's horizon is not applicable to the universe as a whole, since it only works in a stationary spacetime and the universe is not stationary.

So the only real answer to your question is Matterwave's: a second is a second by definition.
 
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1. How is the length of a second determined?

The length of a second is determined by the International System of Units (SI). It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium 133 atom.

2. Has the length of a second always been the same?

No, the length of a second has not always been the same. It was originally defined based on the length of a day, which was thought to be constant. However, with advancements in technology and more precise measurements, it was found that the rotation of the Earth is actually slowing down. In 1967, the second was redefined based on the properties of the cesium atom.

3. How long was the first second?

The length of the first second is difficult to determine as it was not measured with the same precision as it is today. However, based on calculations and estimations, it is believed that the first second was approximately 1/86,400 of a solar day, which is the length of the first day on Earth.

4. Can time be measured in smaller units than a second?

Yes, time can be measured in smaller units than a second. The SI system also includes the millisecond (1/1000 of a second) and the microsecond (1/1,000,000 of a second). Technology has also allowed for the measurement of even smaller units, such as nanoseconds (1/1,000,000,000 of a second) and picoseconds (1/1,000,000,000,000 of a second).

5. Will the length of a second ever change in the future?

It is possible that the length of a second may change in the future as technology and measurements become more precise. However, any changes would likely be very small and would not have a significant impact on our daily lives. The SI system is constantly being reviewed and updated to ensure that the units are as accurate as possible.

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