Duration of light from stars

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Jim_Baur

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How long can the light from a star remain in existence?

THANKS!
 
Jim_Baur said:
How long can the light from a star remain in existence?

THANKS!
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Forever. Light does not decay, though it can be scattered. So it can travel from one end of the universe to the other which will take billions of years. As long as that light is not scattered, then it is there. It is kind of neat, sort of like a natural archive of cosmic history. Imagine if light actually contains more information within it and we can somehow access and decode it? We can watch past events happening from far away as the light are just reaching us today.
 
The above posters are correct. If a photon were not interrupted in its path at all, it could travel from one side of the universe to the other without a qualm.
 
ConstantineTG said:
Iumagine if light actually contains more information within it and we can somehow access and decode it? We can watch past events happening from far away as the light are just reaching us today.
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You’re doing that right now by reading this.
 
dshix said:
The above posters are correct. If a photon were not interrupted in its path at all, it could travel from one side of the universe to the other without a qualm.
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So where are all the photons ever generated that have not hit mass?
 
buffalo said:
So where are all the photons ever generated that have not hit mass?
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Presumably still travelling assuming they’ve not left the boundary of the observable universe. Beyond the observable universe they would be presumed to still be travelling as there have not yet been any indications that the expansion of space time has stopped.
 
Jim_Baur said:
How does entropy play into all of this?

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Since entropy is the amount of energy that is not used for work (i.e., energy transfer) and a photon transfers energy via collisions, then it follows that a photon that does not scatter ever would necessarily increase the entropy of the universe.
 
I think the answer to that question is very complicated. Only a small fraction of the visible universe consists of matter, and detecting some objects is limited by our human vision. Radio telescopes and other devices that operate outside the range of normal human vision can see more.

In our galaxy, the Earth revolves around the Sun and our Solar System revolves around the center of the Galaxy. Supposedly, and as far as I know, even though there is no way to detect it, astronomers are saying ‘dark matter’ exists. This strongly suggests that light from 13 billion years out has a high probability of being deflected for various reasons: absorbed by a black hole, scattering by striking hydrogen atoms, dust particles, micro-meteorites, meteors and larger objects, including planets. There is also the issue gravitational lensing where light is bent by large, massive objects. The fact that we can see back 13 billion years is, in my view, a complete mystery.

I look at it this way, if matter on earth which is supposedly about 6 billion years old still exists, what energy source allows electrons to constantly orbit the nucleus of any given atom? It has been said that over billions of years, the speed at which the Earth orbits the Sun will slow down.

Finally, there may be electromagnetic fields and zones in space that we have not detected or fully taken into account. Plus, picture this: the Hubble space telescope is looking at the Western portion of the universe and sees galaxies out to 13 billion years, so how do we know where we are in relation to that? Are we in the exact center of the Universe? Are we closer to one side than the other?

Peace,
Ed
 
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