Astronomers agree: Universe is nearly 14B years old(phys.org)
phys.org
Astronomers agree: Universe is nearly 14B years old
https://phys.org/news/2021-01-astronomers-universe-billion-years.html
10 comments
Can someone explain what does this claim "x is y years old" even mean?
Isn't time coordinate (of creation of x) dependent on the reference frame of the observer? Which frame is used here?
Isn't time coordinate (of creation of x) dependent on the reference frame of the observer? Which frame is used here?
The interesting question is what was happening 15 billion years ago.
I'm not a physicist, but I believe the current understanding is that there's no 15 billion years ago. Time is a side-effect of measuring entropy, and according to the Big Bang theory you go backwards in spacetime to a point of infinite density and temperature, and there's no "past" that.
Time is most definitely not a side effect of measuring entropy. Time elapsed is defined by number of periods of some (natural or artificial) periodic phenomenon. Orbiting of the Sun, or pendulum swinging, or clock hands motion, or electric circuit current oscillations. None of these periodic processes have anything to do with the concept of entropy.
15B years ago, the requirements started to be gathered. Coding started 14.5B years ago.
That's like asking "what's south of the south pole?"
If extended with given quantity "how far from the south pole", that question actually has definite answer for any observer not on any of the two poles.
The only observer for whom there is no answer is the one on the south or the north pole.
Regarding the time question, are we on Earth in 2021 on the poles of the time sphere, or somewhere in between them?
The only observer for whom there is no answer is the one on the south or the north pole.
Regarding the time question, are we on Earth in 2021 on the poles of the time sphere, or somewhere in between them?
It requires a reformulation of the geometric question. Which is like the question of time. With our current definition/understanding relating to changes and entropy there is no 'further south' so we need to talk about something different to talk further.
Are you saying that we require an insight similar to thinking beyond Earth-centrism?
The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz
- Journal of Cosmology and Astroparticle Physics
[1] https://iopscience.iop.org/article/10.1088/1475-7516/2020/12...