infact this can also be ask in the question and answer forum, but i am writing my question here:

"is it true that the rays which are born in the sun's core require a time of 10yrs (of earth) to reach at the surface? "

my cousin has provide this information, who said to him, he has not attached any kind of details, but he just made this statement.


sunil

I think the average time for a photon to escape the sun is more on the order of 10⁴ years. Of course, a photon is always absorbed and reemitted, so it is not really the same photon that comes out. You can think of it as having a dark sun, then suddenly emitting trillions of photons in the core, it would take some 10,000 years before half the amount would be emitted from the surface.

EDIT: The Bad Astronomer has written a nice page about this: The Long Climb from the Sun's Core

It takes a lot longer than that. From the NASA SOHO site (LINK)

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At night the stars put on a show for free (Carole King)

One Earth, One Sky - IYA 2009

The photons generated at the Sun's core can take a long time to make it to the surface before they can travel unimpeded to the Earth. I've seen estimates between 100,000 years and 1 million years. The Sun is very opaque and a photon will only travel only about one centimeter before it is absorbed by an atom. A photon will later be re-emiited, but more than likely, in a different direction. If you could trace the path of the photons as they are absorbed and re-emitted you would see it as a crazy zig-zag pattern.

You can contrast this with the path of a neutrino. A neutrino interacts very weakly with matter and most will pass directly through the entire volume of the Sun without any interaction. The neutrinos we manage to capture on Earth tell us what's going on in the Sun's interior as it was about 8 1/2 minutes ago.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

Thats about the same figure i read about also.

However the absorbtion and re-emision it total random as far as direction. Some few photons make it to the surface in days, maybe minutes by taking a randomly direct path to the surface (about 1 out of 10 trillion) like wise, a rare few will also never make it to the surface.

Also a few rarer photons make it to the surface at close to light speed, via quantum tunneling effect.

Unfortunately the amount of these are so few, from both random strait path and q-tunneling, that they can't be used to determine whats going on from inside the sun. I can't remember the exact figures, but the random strait path photon count was estimated at something like 10 per year, and the Q-Tunnel effect about 1 every 2 years.

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"There is no problem that cannot be solved by a suitable application of high explosives" - US Army Demolitions School

http://worldsofothersuns.home.comcast.net/

I admit that I haven't researched it, but notes that Phil writes this:

The complicating issues are:

1) that no one photon "makes it" to the surface of the Sun (or even the top of the radiative zone). As stated above, "real photons" interact with the local matter and exchange energy with it (created, destroyed, created, ...).

2) and even if you pretend that they did, the "travel time" of the photons is broadly and asymmetrically distributed in time with a long tail toward longer times, so you can hear all sorts of numbers of years quoted even if everyone is looking at the same distribution function (peak, average, median, rms, etc).

As others have pointed out, an individual photon never makes it out of the sun. Each collision with matter transfers energy to the matter, the original photon is absorbed and a new one emitted.

For the rest of my post, I'll just refer to the path taken as the pseudo-photon. As part of the thought experiment, we can treat it as if the same photon were being emitted from the matter after collision, even though it's not. It simplifies things though.

All of these collisions alter the path of the pseudo-photon. Think of it like those game show contests where a ball or puck is dropped from a height onto a series of posts before reaching the bottom. The classic is Plinko, seen on The Price Is Right in America.

(For a more humorous take, you can see variants on Spike TV's MXC.)

The pseudo-photon is affected by the matter it collides with in a similar way to the Plinko chip. Each thing it hits causes its course to be changed, making its journey erratic, rather than a straight line. This will have a drastic effect on the amount of time it takes to actually reach the surface and be emitted into space.

I'll let someone else more educated in physics tackle whether or not energy is lost between the collision and emission of the new photon, which will also affect the course & time taken.

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"Reality is that which, when you stop believing in it, doesn't go away."
Philip K. Dick, Do Androids Dream of Electric Sheep?
"A lie can travel half way around the world while the truth is putting on its shoes."
Mark Twain

Avatar courtesy of Bunny.

IIRC, isn't this the "Drunkard's Walk" or Random Walk mathematically?

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At night the stars put on a show for free (Carole King)

One Earth, One Sky - IYA 2009

very nice information you all have given and with the links, means imagine that in the core of sun itself the rays are reaching on the surface in say "10" years, but on earth they are quite early reaching, see the vast difference!

sunil

Similar, and probably a 'good enough' model for what we're talking about. The difference is that, as I understand it, the Random Walk requires that each 'step' be the same distance. In the sub-atomic world, there's no such guarantee.

__________________
"Reality is that which, when you stop believing in it, doesn't go away."
Philip K. Dick, Do Androids Dream of Electric Sheep?
"A lie can travel half way around the world while the truth is putting on its shoes."
Mark Twain

Avatar courtesy of Bunny.

That is not the case (otherwise it would be useless). In calculations you use the average distance, which of course is the same each step.

You could always use a random step size with some reasonable distribution in a random walk simulation also, if need be. If I'm thinking correctly here, the average step length should apply as the step length for the RMS distance being < root(n)*step length.

In that case, I think the Wikipedia entry needs to be clarified. That's how it read to me. Hm.

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"Reality is that which, when you stop believing in it, doesn't go away."
Philip K. Dick, Do Androids Dream of Electric Sheep?
"A lie can travel half way around the world while the truth is putting on its shoes."
Mark Twain

Avatar courtesy of Bunny.

I don't know about that. The easiest example is always same distance step, so introductionary material tend to use it. Eg:
The bolded part is only a restriction for the simple case. When they discuss Brownian motion, it is at least implied that the length of the steps varies.

But you're right, it should probably be written out clearly somewhere, although I don't dare meddling in the affairs of mathematicians

Would the larger radial rms produce the outward walk?

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Your avatar may even attest to that.

On topic, a constant step size is the usual beginner case; I have no idea if a random step size is used in some cases, but I would be the type to use it if it fit the scenario.