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Does light have an infinite lifetime?

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Re: Does light have an infinite lifetime?

#41

Post by dylan604 »

adonovan wrote: post #38
doodlebugging wrote: post #37

Where do the photons that hit my retina go when I finish with them? If they have infinite lifetimes then does each one carry a memory of it's creation event? When I burn a log in my fireplace and a cinder flares and pops creating a spark, does the photon exist after the spark energy flares out and the cinder is no longer illuminated enough to be detected by my eyes? If photons are infinite then harvesting light would…

Feynmann is very clear that the photons bouncing off a mirror are not the same ones that hit it. They are absorbed by electric oscillators (free electrons in the material) and destroyed; then new ones are created and emitted. He's also careful enough to point out that electrons don't really have an identity that would allow you to meaningfully define "not the same". :)

Electrons? We were just told that there is only one single electron in yesterday's posts. It's almost like they don't know what an electron is

Re: Does light have an infinite lifetime?

#42

Post by cwoolfe »

pc86 wrote: post #22
cwoolfe wrote: post #14

"God is light." (1John 1:5)

Do you have something constructive to add related to the content of the article or are we just quoting random bible verses on HN for no reason?

"The light shines in the darkness, and the darkness can never extinguish it.

God sent a man, John the Baptist, to tell about the light so that everyone might believe because of his testimony. John himself was not the light; he was simply a witness to tell about the light. The one who is the true light, who gives light to everyone, was coming into the world.

He came into the very world he created, but the world didn’t recognize him. He came to his own people, and even they rejected him. But to all who believed him and accepted him, he gave the right to become children of God."(John 1:5-12)

Re: Does light have an infinite lifetime?

#43

Post by doodlebugging »

dylan604 wrote: post #41
adonovan wrote: post #38

Earlier quoted context omitted.

Feynmann is very clear that the photons bouncing off a mirror are not the same ones that hit it. They are absorbed by electric oscillators (free electrons in the material) and destroyed; then new ones are created and emitted. He's also careful enough to point out that electrons don't really have an identity that would allow you to meaningfully define "not the same". :)

Electrons? We were just told that there is only one single electron in yesterday's posts. It's almost like they don't know what an electron is

I believe they're right about there being only one single electron. I tried to start my Pathfinder yesterday and it was dead as a doornail. None of the dash lights lit and there was not even a click from the starter. Someone else must've been using that electron though since I tried again a few minutes later and it cranked right up. I had my turn with it so I'm not mad at all.

Re: Does light have an infinite lifetime?

#44

Post by AlexAndScripts »

prettydeep wrote: post #34
gwern wrote: post #2

Interesting. I had no idea that the universe would eventually be basically just photons. I wonder if that is why Stephen Baxter had his 'photino birds' as the final form of life in his Xeeleverse?

Roger Penrose has a theory about a cyclical conformal universe, which requires that the universe eventually only contains photons. As photons travel at the speed of light, they do not experience the passage of time, so they also do not experience distance (space). So in the deep remote future, when only photons are left, the difference between the very large and miniscule disappears, and you get all photons in the un…

https://en.m.wikipedia.org/wiki/Conformal_cyclic_cosmology

It seems the paper made mistakes, using a non-standard model of the CMB that failed upon replication. It's an interesting theory thoughb.

Re: Does light have an infinite lifetime?

#45

Post by kloop »

codyd51 wrote: post #16
barfbagginus wrote: post #10

Earlier quoted context omitted.

The photino birds want the universe to be populated with white dwarfs, because they can feed off their gravity wells without the risk of deadly supernovas and black holes, which can kill them. After the xelee and humans leave, the universe becomes a cold place dominated by photino birds living in the cold pinpricks of white dwarfs. Eventually matter evaporates into photons, and the photino birds die. However, it turn…

One potential hiccup with your one-photino-bird-universe theory (which is quite fun!): I believe I remember a scene in which the ‘birth’ of a photino bird was described. If I remember correctly, it was indeed described as a clone of its parent.

As long as we only see one birth, that's probably fine. It just implies a stable time loop.

Re: Does light have an infinite lifetime?

#46

Post by AgentME »

adonovan wrote: post #38
doodlebugging wrote: post #37

Where do the photons that hit my retina go when I finish with them? If they have infinite lifetimes then does each one carry a memory of it's creation event? When I burn a log in my fireplace and a cinder flares and pops creating a spark, does the photon exist after the spark energy flares out and the cinder is no longer illuminated enough to be detected by my eyes? If photons are infinite then harvesting light would…

Feynmann is very clear that the photons bouncing off a mirror are not the same ones that hit it. They are absorbed by electric oscillators (free electrons in the material) and destroyed; then new ones are created and emitted. He's also careful enough to point out that electrons don't really have an identity that would allow you to meaningfully define "not the same". :)

Electrons aren't unique in not having identities. Photons of the same wavelength are similarly fungible if I remember right, though it's a little more defensible to call the reflected light not the same photons since the original photons are transformed to something we don't call photons before photons are produced again.

Re: Does light have an infinite lifetime?

#47

Post by doodlebugging »

adonovan wrote: post #38
doodlebugging wrote: post #37

Where do the photons that hit my retina go when I finish with them? If they have infinite lifetimes then does each one carry a memory of it's creation event? When I burn a log in my fireplace and a cinder flares and pops creating a spark, does the photon exist after the spark energy flares out and the cinder is no longer illuminated enough to be detected by my eyes? If photons are infinite then harvesting light would…

Feynmann is very clear that the photons bouncing off a mirror are not the same ones that hit it. They are absorbed by electric oscillators (free electrons in the material) and destroyed; then new ones are created and emitted. He's also careful enough to point out that electrons don't really have an identity that would allow you to meaningfully define "not the same". :)

I wonder about the all the photons lost in fiber optic installations. What happens to them in their short lives? There must be a creation and an extinction event.

A photon jumps into the glass fiber and travels until it encounters an opto-electric coupler where the photon craps out and is converted to an energized stream of electrons, or maybe it borrows the only real electron in the universe for an instant as it flips across the coupler to the next glass fiber where a new photon is born, only to flare out at the next junction.

Re: Does light have an infinite lifetime?

#48

Post by westmeal »

doodlebugging wrote: post #43
dylan604 wrote: post #41

Earlier quoted context omitted.

Electrons? We were just told that there is only one single electron in yesterday's posts. It's almost like they don't know what an electron is

I believe they're right about there being only one single electron. I tried to start my Pathfinder yesterday and it was dead as a doornail. None of the dash lights lit and there was not even a click from the starter. Someone else must've been using that electron though since I tried again a few minutes later and it cranked right up. I had my turn with it so I'm not mad at all.

Um maybe check your battery terminals for corrosion :)

Re: Does light have an infinite lifetime?

#49

Post by doodlebugging »

AgentME wrote: post #46
adonovan wrote: post #38

Earlier quoted context omitted.

Feynmann is very clear that the photons bouncing off a mirror are not the same ones that hit it. They are absorbed by electric oscillators (free electrons in the material) and destroyed; then new ones are created and emitted. He's also careful enough to point out that electrons don't really have an identity that would allow you to meaningfully define "not the same". :)

Electrons aren't unique in not having identities. Photons of the same wavelength are similarly fungible if I remember right, though it's a little more defensible to call the reflected light not the same photons since the original photons are transformed to something we don't call photons before photons are produced again.

But at a reflection event you aren't producing a new photon, you are only reflecting a portion of the original determined by the refractive indices of the reflection interface. At that interface, part of the original photon is reflected and the rest is transmitted across the interface as a new photon and both have a modified bandwidth relative to the parent photon. So the one you see reflected is the same photon after modification by the medium it traversed and the transmitted components escape your view unless you are monitoring the other side of the medium.

Re: Does light have an infinite lifetime?

#50

Post by xyzelement »

cwoolfe wrote: post #14

"God is light." (1John 1:5)

Genesis 1:3 has: "And G-d said, Let there be light, and there was light[0]." This says on the literal level that light is a created thing distinct from G-d, and thus finite (though created very close to the creation of the universe itself, on day 1).

To be clear, light is a very common metaphor for G-dliness in Judaism and the quote from John resonates as a perfectly fine metaphor, rather than a literal assertion of equivalence.

[0] "וַיֹּ֥אמֶר אֱלֹהִ֖ים יְהִי־א֑וֹר וַֽיְהִי־אֽוֹר"

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