
The Long Climb from the Sun's Core (1997) - georgecmu
http://www.badastronomy.com/bitesize/solar_system/
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pavel_lishin
_The center of the Sun is extremely dense, and a photon can only travel a tiny
distance before running into another hydrogen nucleus. It gets absorbed by
that nucleus and the re-emitted in a random direction. If that direction is
back towards the center of the Sun, the photon has lost ground!_

It's not really the _same_ photon, though, is it? It's just some measure of
energy.

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breadbox
What do you think a photon is but a measure of energy?

Imagine you shoot a puff of air across a room (presumably using an Air-
zooka(R)) and score a direct hit on me. If I turn around and say, "I can't
believe that puff made it all the way across the room," you could object to my
comment by saying "It's not really the _same_ puff of air; most or all of the
molecules in the original puff are still over here." But this just obscures
the fact that a puff of air, as people use the term, really refers to the wave
pattern of cause and effect that travelled across the room. The gas molecules
that are inside such a puff at any given moment are incidental and ultimately
not what I'm talking about.

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leeoniya
isn't it a bit odd to call light "old" since it's the one thing that actually
does not age by definition. i understand they're just counting the time from
when it was first emitted, but still...

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arethuza
Sort of related to that, is it valid to say it is the "same" photon that is
absorbed and re-emitted?

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leeoniya
maybe they're just trying to live up to the domain name :)

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speeder
Whoa,! This is something I did not knew, and I do read a lot about the sun...
But bouncing photons? I never imaginated that, totally awesome.and amazing!

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jffry
You should also read about how stars form and evolve over time:

* [http://en.wikipedia.org/wiki/Stellar_evolution](http://en.wikipedia.org/wiki/Stellar_evolution)

* [http://en.wikipedia.org/wiki/Main_sequence](http://en.wikipedia.org/wiki/Main_sequence)

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loxs
Quite an old article. Anyone know a more recent estimate about the time it
takes a photon to ascend?

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edoloughlin
In the Secret Life of The Sun
([http://www.bbc.co.uk/programmes/b03694kd](http://www.bbc.co.uk/programmes/b03694kd)),
a popular science program, I remember they gave a range of between 10,000 and
1,000,000 years and mentioned 100,000 as the average later in the programme.

