[neilep (OP)]

Dearest Sunoligists,


Here is the Sun:



The Sun...moments ago...Actual size !!




Now we all know that Photons take's approx 100,000 years to escape the Sun. Does that mean that after Fusion commenced ..... the Sun did not shine for 100,000 years ?


Whajafink ?




Hugs et les shmisheys


mwah mwah mwah !




Sheepy
xxxx
Sun rhymes with 'bum' lol chortle..snigger...guffaw !!




 

[Halc]

Always the interesting questions, and this one is eggseptional!  Wait, that's the "why did the chicken cross the road" question.  Sorry.  This one has deep ramifications.

Now we all know that Photons take's approx 100,000 years to escape the Sun.

And neutrinos thus generated take about 2.5 seconds to do the same thing.
The average quanta of energy released in some random internal action takes a thousand centuries, yes. The photon lasts a teeny fraction of a second and is absorbed by something, at which point it is no more. That thing abserbing it is also hot so a new one is generated (maybe a different frequency, who knows?).  This random brownian motion doesn't allow fast travel, so yea, heat generated from within takes all that time to escape, just like it does on Earth. Convection probably has more to do with it than does radiation.

Does that mean that after Fusion commenced ..... the Sun did not shine for 100,000 years ?

That's the interesting question. The sun was not as big and was not so defined back when fusion commenced. It was already hot just from all that mass falling into that gravity well, so it already shone at that point, but a dull infra-red radiation of heat, not proper fusion light. That light did just suddenly blink on, so there's no clear beginning of it and no clear point where special kind of light began to hit the surface.
But yes, fusion light was not there until there was fusion, and that significantly heated up the core of this forming star, and that threshold occurred at say time X, and at a low level. How long after time X did the external spectra of the star change?  It didn't just blink on like a light bulb, so it's really hard to measure.

I imagine that the specific energy of that process (which presumes a nonsense idea that energy has identity) was already taking a better part of that 100000 years to get to whereever light was free to escape without immediately being reabsorbed. But I also imagine that some of that new heat propagated up much faster (by chance and by change of dynamics) so that the external appearance of the star became visibly different within a few days to years (and not centuries) of fusion starting. I mean, a supernova starting at a stellar core is such a change in dynamics, a far more severe one in a start that has far further to go to get to the surface. That change takes around what, 4 hours? to get to the surface (as evidenced by neutrinos from the explosion getting to Earth 4 hours ahead of the light).

The question is more about the time to 'blink on' than it is about how long it took the energy of a specific reaction to reach the surface back in those days, so I am going with the days/years figure and not the thousand centuries.

Sun rhymes with 'bum' lol chortle..snigger...guffaw !!

No it doesn't, any more than do the lines "Glory streams from heaven afar; Heavenly hosts sing haleluyar" (OK, but that was a rhyme stolen from "Blazing saddles").

[alancalverd]

Sun rhymes with 'bum' lol chortle..snigger...guffaw !!

Oh no it don't, Mary Poppins.
Norf of the river it's the old currant bun, dontcherknow.
You mutton or summink?

[neilep (OP)]

Always the interesting questions, and this one is eggseptional!  Wait, that's the "why did the chicken cross the road" question.  Sorry.  This one has deep ramifications.

Now we all know that Photons take's approx 100,000 years to escape the Sun.

And neutrinos thus generated take about 2.5 seconds to do the same thing.
The average quanta of energy released in some random internal action takes a thousand centuries, yes. The photon lasts a teeny fraction of a second and is absorbed by something, at which point it is no more. That thing abserbing it is also hot so a new one is generated (maybe a different frequency, who knows?).  This random brownian motion doesn't allow fast travel, so yea, heat generated from within takes all that time to escape, just like it does on Earth. Convection probably has more to do with it than does radiation.

Does that mean that after Fusion commenced ..... the Sun did not shine for 100,000 years ?

That's the interesting question. The sun was not as big and was not so defined back when fusion commenced. It was already hot just from all that mass falling into that gravity well, so it already shone at that point, but a dull infra-red radiation of heat, not proper fusion light. That light did just suddenly blink on, so there's no clear beginning of it and no clear point where special kind of light began to hit the surface.
But yes, fusion light was not there until there was fusion, and that significantly heated up the core of this forming star, and that threshold occurred at say time X, and at a low level. How long after time X did the external spectra of the star change?  It didn't just blink on like a light bulb, so it's really hard to measure.

I imagine that the specific energy of that process (which presumes a nonsense idea that energy has identity) was already taking a better part of that 100000 years to get to whereever light was free to escape without immediately being reabsorbed. But I also imagine that some of that new heat propagated up much faster (by chance and by change of dynamics) so that the external appearance of the star became visibly different within a few days to years (and not centuries) of fusion starting. I mean, a supernova starting at a stellar core is such a change in dynamics, a far more severe one in a start that has far further to go to get to the surface. That change takes around what, 4 hours? to get to the surface (as evidenced by neutrinos from the explosion getting to Earth 4 hours ahead of the light).

The question is more about the time to 'blink on' than it is about how long it took the energy of a specific reaction to reach the surface back in those days, so I am going with the days/years figure and not the thousand centuries.

Sun rhymes with 'bum' lol chortle..snigger...guffaw !!

No it doesn't, any more than do the lines "Glory streams from heaven afar; Heavenly hosts sing haleluyar" (OK, but that was a rhyme stolen from "Blazing saddles").

Thank ewe so much for your kind and very interesting answer. Yes, I should have worded the question specifically towards the 'Fusion Light'  Great answer Mr Halc  I have learned stuff.....

[neilep (OP)]

Sun rhymes with 'bum' lol chortle..snigger...guffaw !!

Oh no it don't, Mary Poppins.
Norf of the river it's the old currant bun, dontcherknow.
You mutton or summink?

Let's ask an AI ?


"Yes, "sun" and "bum" have a similar ending sound but do not technically rhyme because their vowel sounds are different. "Sun" has the "uh" (/ʌ/) sound, while "bum" has the "uh" (/ʌ/) sound as well, but the consonant sounds leading into the vowel are different."


 

[Halc]

Let's ask an AI ?


"Yes, "sun" and "bum" have a similar ending sound but do not technically rhyme because their vowel sounds are different. "Sun" has the "uh" (/ʌ/) sound, while "bum" has the "uh" (/ʌ/) sound as well, but the consonant sounds leading into the vowel are different."

That is a spectacularly wrong answer to an amazingly simple question, even for an AI.
It says they don't rhyme (true), but for all the wrong reasons.
1) The vowel sounds are different, as evidenced by them being exactly the same.  Hmmm...
2) OK, they maybe don't rhyme because " the consonant sounds leading into the vowel are different".  Well the are admittedly different, so according to AI, "sheep" and "heap" don't rhyme.
It's actually the consonant sounds trailing the vowel that need to be the same.

All the more funny because AI actually knows how to rhyme since it will write a passable poem (complete with meter) if you ask it.

[alancalverd]

Moon, spoon, June, croon, prune, lagoon....How on earth did Tin Pan Alley get away with what Augmented Idiocy considers to be non-rhymes?

[evan_au]

"Brown Dwarf" stars >13 times the mass of Jupiter will start deuterium fusion, at a slow rate.
https://en.wikipedia.org/wiki/Brown_dwarf

So the Sun could have started to heat up long before it reached its current mass.
- But this slow fusion would have been lost in the heat of the friction and infalling matter which formed the star out of the protoplanetary disk.
https://en.wikipedia.org/wiki/Protoplanetary_disk

Fusion of normal hydrogen starts when a star is the size of a red dwarf (10% of the mass of the Sun), using the proton-proton chain.
- For stars larger than the Sun, fusion via the CNO process dominates
- The Sun itself uses both processes to generate heat
https://en.wikipedia.org/wiki/Stellar_nucleosynthesis

It seems to me that as a star gains mass, it's temperature increases. When fusion starts (long before the Sun reached its current mass), the temperature increased more rapidly. One way to tell when fusion starts is to detect neutrinos (and measure their energy to determine what reactions are producing the neutrinos).